palerider

Today I tested many times the pink wire on the 2 wire coil connector. With engine on I had power, but when I cranked it over the power light went off. Now the white wire did not flash at all. I then removed that ICM amd replaced it with an old GM one that tested good at Napa. I then got power on the coil pink wire and flashing light on the coil white wire.But still no run (we can smell gas a bit now)I hate to admit it but I forgot all about the plugs. I pulled # 1&3 (easiest) and they were extremely fouled. Did the old lay on the block and crank it over test and the fire was little to none. I CLEANED THEM UP RECHECKED THEM AND THE FIRE WAS MUCH BETTER. wILL REPLACE ALL TOMORROW WITH ngk MAYBE A LITTLE HOTTER.As well I will do the test you mentioned in your narrative. Thank you!!! Also I pulled out the ECM and the PROM, reseated the PROM, reinstalled the wiring harness and reinstalled the ECM unit as utilityguy2 suggested. I checked all the fuses and replaced them regardless. The one behind the battery is referred to in the schematic as a fuel pump fuse and the ECM fuse is in the insde panel along with the 2 injector ones.Am hoping now that I can get good spark from the plugs so as to tell the injectors to fire if that is the way things work.

palerider

There are 2 pink and 2 white wires at the coil. I am probing the gray 2 lead holder. Is that what I should be doing not the 4 place one?

palerider

Well todar 1 Mar 2012, I replaced all the spark plugs as the others were fouled to the max. I checked the pink wire on the 2 wire lead from the dizzy, engine off = the test light was on. I then switched to the white wire on the 2 wire lead from the dizzy, with engine on and cranking I had a flashing/blinking test light. I then checked for spark ftom the coil to the distributor= a strong, steady blueish fire. I did not disconnect the 4 wire leadfrom the dizzy. I then attemted to start the engine and nothing . I mean crank/ no start condition remains. Thank you all for your help. If there is anything else please chime in anyone.

884+3

OK it sounds like you have good spark so now on to the fuel side of things. What does the noid light show? Have you checked the fuel pressure? What is your tps set at?

palerider

The last noid light test showed no pulse at all. (none of the lights would flash). I am going to do a ohm test on each one now (isn't that just as good?)You just leave the injector in the rail disconnect the terminal and probe the injector key off, look for 16K Ohms. Fuel pressure is good 45-48 PSI. The TPS was last set at .54 when it was running. Can you do key on/no run test? That way I could recheck it. Thanks 884+3.

palerider

I redid the noid test same no pulse. However I do now have power to the pink lead on the 2 wire coil harness and the white lead does show a strong pulse when cranking. We have strong spark at the coil and at the plugs. Fuel pressure is 46-48 PSI.
The injector connect-harness shows power as well. But still no run. I will check the VATS fuse in the convenience center where ever that is tomorrow and follow up on the wiring. I may replace the ignition switch as it is hard to rotate sometime. I am about ready too shoot the thing at this point. I really do appreciate all the effort you folks have given me. If it even pops once I will post it. And if anyone else has any suggestions please let me know. Thank you!

utilityguy2

iTrader: (1)

Remember, VATS is part of your ignition switch. If you sprayed any lubricants or oils into the switch, VATS may fail. I know we over this before but I'm wondering if maybe it is the switch. Can it signal starter and not injectors? hmmm

utilityguy2

iTrader: (1)

Also, you seem to say the injector harness has power. So that means your injector fuses are OK. Are you sure the ecm fuse in the panel is OK? The ECM batch fires the injectors by grounding them. I don't see in the wiring diagrams any wiring connection between the passkey decoder and the injectors as there is to the starter enable relay. I believe the ECM needs to see the correct resistance from the decoder to enable the injectors. If that is so there could be cranking but no injectors because the starter enable relay has been satisfied but ECM has not. But what would cause it? Irocmenace any input?

palerider

Not a thing has been sprayed into it unless my friend did thinking he was doing me a favor. But we have come a log way and this seems to be all that makes any sense at this time. In fact I have never checked or seen a VATS fuse. Will get to it tomorrow. Yes I have checked the ignition/ECM. fuse in the inside driver floor panel. Thanks utilityguy2

utilityguy2

iTrader: (1)

Looking at the wiring diagrams, there is no "fuse" for the VATS. There is a fusible link that powers the switch, starter enable relay and the pass-key decoder module. If that was blown you would have a no crank no start condition but yours does crank so it appears to be OK.

palerider

I guess I am stuck at this point. Some one mentioned a fuse that ran somewhere under or by the brake booster. I will try to look for that.

utilityguy2

iTrader: (1)

That may be the fusible link I mentioned. a rusty brown link on red wire.

palerider

Glad you told me it was a fusible link, in the schematic it just shows a 10 or 20 amp fse

ASE doc

As has been said already, if the engine cranks, the power to the ignition switch is okay. Do, however, verify that you have power to both the injectors and the coil when cranking. VATS may well be your issue. There is a detailed test sequence for the VATS system here on TGO in the tech articles. Ypou basically test for resistance at the two wire connector coming from the ignition switch to verify that the contacts at the key are good. Then you can use a volt meter to look for voltage at the blue wire to the ECM. The blue wire, which is the fuel enable circuit actually should have a 5 volt square wave. Your DVOM will read about 2.5 volts if the signal is there.

Its odd though that you had fuel fouled plugs if there was no injector pulse. I would suggest carefully rechecking things. Have you reference timed the distributor? Are the injector fuses okay?

palerider

I replaced the ignition swtch today but the dealer did not have the required VATS key. I am having some trouble compressing that spring far enough down to get the retainer ring around it. Not as young as I used to be. I did not see a dark blue wire when doing this. Only 2 white very thin ones from the new switch. The reason we had very fouled plugs was the vehicle barely limped home and it was running very rich. It quit in the garage and you know the rest of the story. Will it be necessary to check the dark bue wire for voltage now that we did put a new ignition switch in it? Appreciate your help ASEdoc.

ASE doc

The small wires from the key cylinder can be tested for resistance. With the key in they should read very close to the key pellet's resistance. If you know the key code, you can find the resistance, or just use your ohmmeter on the key. The dark blue wire is from the VATS module to the ECM. I don't have time right now to locate these parts for you. If you need me to I will as soon as I have a chance. There is a special tool for compressing the spring under the steering lock ring. I bought the same one I still use today for $20 at the local parts store.

palerider

Frustrated I pulled the whole distributor and replaced it due to to no injector pulse. We have power at the pink wire engine on/cranking with the 4 prong distributor disconnected from distributor. We have NO LIGHT/NO PULSE (NEGATIVE GROUND) to the white wire engine on/cranking, however as we were leaving for the day we said lets give it a shot of ether and try it. She popped for the first time so it seems fuel release is the problem.( all wires to the dizzy connected) About the only thing I have not replaced is the Electronic Spark control module and I am wondering if it could be a player in this scenario?. Is their a way I can test it? I never could fond a dark blue wire to test the voltage. Another thing I pulled the new connector off the new ignition key switch. I USED WEATHER PROOF SOLDERLESS BUTT CONNECTORS TO REDO THE CONNECTIONS. CHECKED WITH EVERYONE I COULD WITH ANY KNOWLEDGE OF RESISTANCE AND THEY SAID THE CONNECTION WOULD BE FINE, I OHM TESTED THE SWITCH WITH THE KEY IN AND IT matched the specifications. Even with the schematic I cannot locate the vats module. Would it matter which one of the wires from the key switch went to the connector? I tryed the wires both ways with no results before butt connecting them. It also seems I have lost my Pulse on the distrubutor white wire engine on/cranking that I had earlier. But with the shot of ether she did pop. I sincerely thank you for your inputs ASEdoc!

IROCmenace

iTrader: (1)

Vats modules I have found were against the firewall on the d/s sandwhiched between the dash and firewall. The ones I have seen were on the driverside part of the firewall on a 91 RS and towards the center of the firewall in an 89 Formula, even worse to get to. I believe it is a grey plastic box. about 4" by 3.5" and about 1" think. One connector in. A real turd to get to. You do not have to remove the dash, but you basically have to unbolt everything that holds it in and roll the top of the dash towards you. Hidden there for security reasons I guess.

.

One other thing you could check may be a longshot or might not. TPI cars have a failsafe that if the sensor above the oil filter no longer reads pressure it will cut the engine off to save the engine. I have seen this in practice due to a buddy with a T/A that was running low on oil, the car would die on harder stopping situations (no he was not very smart to let this happen).
May check that sensor. Cheap to replace.

I can't remember if it cuts the injectors off or the fuel pump off but on my recent engine replacement I had not plugged that sensor in yet and the car would not start.

palerider

Thanks for the tip. I will see if I can locate it. I think I am going to OHM each injector as I see one bad one will shut down a hole bank and possibly all injectors. I only need to pull the 2 wire cable or do I need to remove the entire injector and probe each terminal or can that be done with them installed in the vehicle? Thanks IROCmenace

utilityguy2

iTrader: (1)

Just pull the injector wire connector off and test between the two terminals. The oil pressure switch closes at 4 psi which keeps the fuel pump relay engaged. If no pressure the fuel pump shuts off and turns on the oil indicator light. on the relay there is a wire called fuel pump test connector which you can use to see if relay is engaged. The fuel pump oil pressure switch is located above the oil filter.

palerider

As I understand it TEST 1-- I need to pull all 8 injector connectors (parellel circuit)to test the ohms (resistance). With key off put the DVOM probe gently in each injector and look for 16 ohms. Now for TEST 2--, I check for 12 volts at each connector terminal (2) by grounding the terminal w/key on. TEST 3-- I test each injector w/key on and appling 12 volts to the injector to see if it clicks.
I replaced the oil pressure sending unit and when we crank it over, you can see it rise to about 10-15 PSI. The oil indicator light does not stay on during this process. I also have replaced the fuel pump relay. Could you tell me more about tthe relay test wire. Many regards utilityguy2.

utilityguy2

iTrader: (1)

Your procedure seem ok. The main thing is all injectors should have nearly same resistance I think around 15 ohms or so.
Be aware that there are two oil pressure senders one is a pressure sender for the oil pressure gauge and one is a open close switch. Both look similar.

Actually, the fuel relay test wire can be used to power the fuel pump. simply connect a 12 source to the wired plug and it will run the pump bypassing all of the relay and VATS stuff. It is meant to "test" the pump to see if it is good or bad. The wire is located next to the fuel pump relay on the firewall in a bank of relays. it is the only wire with a connector not connected to anything.

IROCmenace

iTrader: (1)

there is also a port on the ALDL port that you can run a wire from a hot on the fuse box to it to test the pump.

utilityguy2

iTrader: (1)

I've seen it on some but not all. Don't know why. It would be terminal G the bottom row all way left. I'd be very careful doing that as sending 12v to wrong terminal and you now have bigger problems.

ASE doc

You're getting good advice on this thread and I don't want to be redundant. Therfore I think I'll sit back watch your progress for a bit. If I think I may be able to be of additional help I will certainly chime in. Otherwise, I think I'll just watch for now. A few comments I will make: The test for PIP on the white wire has to be done with the test light ground clamp on Batt+ for clear results.

You may want to verify spark KV. A cheap adjustable spark tester will work to verify 40KV at a few plug wires. When testing injector pulse, be sure you verify 12V to the black wire. Then you can check for a flashing light on the black/pink wire with the test light ground clamp on batt+. Or just use a noid light. You can also use a stethiscope to listen for injector click while a helper cranks the motor. Of course you may want to recheck fuel pressure just to be sure. You can ohm test the injectors in banks by accessing the injector circuits at the ECM. Just multiply the reading by 4. If the answer is less than 12, you may have a shorting injector coil on that bank. One thing that may be vexxing you and that I haven't heard mentioned is a clogged CAT. You can check for this by removing the O2 sensor and cranking the engine. Of course verify you're getting good spark and fuel to the cylinders first.

In my work, whenever I perform a repair and the car doesn't operate the way I expect it to, I always go back to the basics and recheck to be sure that nothing has changed. Always recheck your work so that you don't overlook something you may have missed. Test and retest and then double check your test results. Otherwise you can end up running in circles. The worst mistake we can make is to start grabbing at straws, replacing parts because someone said that this fixed their car that had a problem that sounds kind of like what your car is doing. What you may end up with is alot of good test parts and an empty bank account.

An engine needs the following things to run: Compression, fuel, sufficient spark in close to the correct time, and an unobstructed exhaust path. If you can verify these things, the engine has to start. The laws of physics dictate this. Don't give up. It's just a machine and with diligence you will find the problem.

palerider

My question at this point is I have done a fuel pressure test 3 times and all 3 the pressure was within spec 45-48 PSI. So we know the fuel pump is working up to the relay that recieves the go/no go from the Ignition control module , which is regulated by inputs from the coil and ECM. Please point out where I am wrong. I even replaced the Fuel relay module. But I must admit that you have me stumped on this second sensor located above the oil filter in addition to the oil sendind unit!!!
Again I ask the question could the Electronic spark control module be a show stopper in this sceniario? We have not talked about that.
Thanks to all for your much needed assistance.

ASE doc

Verify compression, spark, fuel pressure when cranking, and injector pulse. If these things are all there, check for a clogged exhaust as I mentioned above.

Reread my last paragraph.

palerider

You have made some very fine points and I will adhere to them at this time, Not to disregard my fellow members who are so diligently trying to help me as well. I feel I am going around in circles at times. A lot due to my part.
Back to basics this car popped with the ether so it has good spark. Now we need the injectors to pulse. I will add that when It limped home it felt like it was running on one bank of cylinders. That is why I what to check each one as one will knock out a whole band.I read this on another thread.

IROCmenace

iTrader: (1)

There are two sensors for oil psi; one on the back of the engine (gauge) and one on the driverside above the oil filter (failsafe)

As far as the ESC, I have not had one fail in over a dozen thirdgen's so hopefully someone else can chime in, but I thought you said you had spark. As far as I know the ESC is timing related and not fuel related.

Since you have spark, fuel pressure and no power at the injector harness I wonder if while it was sitting something else happenned like a rodent eating though a ground or some other wire related to injector pulse.

I am running out of ideas because from what you have tested and replaced it would seem the car should run.

palerider

I do have spark. Bad call on my part!

palerider

Again, I hate to admit but there is evidence of mouse or rat droppings.

IROCmenace

iTrader: (1)

I edited my post like four times. My bad I missed some other posts. It is batch fire so one side and other side. I will have to refresh my memory on the wiring diagrams but I think we may be looking at a bad wire or ground issue. I work in insurance and you would be surprised how often mice will eat wiring. I will check some stuff in my books and on my car and get back to you if you haven't got an answer yet.

utilityguy2

iTrader: (1)

Getting to be such a long thread that we are going over things already mentioned but to long to read every time to see that. Just another shot in the dark and I know you said you have spark. How many miles on the engine? Is it possible that the timing chain may have jumped jumped? I know you said it ran bad before you parked it and then wouldn't start. That's classic for jumped chain. Have you checked for spark at top dead center? You probably timed it, was it off? just throwing ideas at this point as it is hard to tell what has been done or not done.

palerider

Sorry about the long thread but when I redo something someone has suggested I like to summarise. I will be more turse.There are 77,000 miles on the vehicle. Yes I timed it and used the bypass. When I put the new distributor in I marked it and placed it in the same position. It did not run bad before we parked it. I did get it to pop real good with a shot of ether 2 post ago. So fuel is the problem. As ASEdoc said I need to check the fuel components as I mentioned in those 4 test post number 71. I have read practically every thread on injectore, fuel problems etc in this forum. It will go here soon I hope. You mentioned a sensor above the oil sending unit/FP one.that could stop fuel post # 72. I am not familar with another component in that area that could cut off fuel. If you are please let me know. Thanks utilityguy2

utilityguy2

iTrader: (1)

IrocMenace also mentioned it in post 79. It is a fail safe switch that needs to see 3 psi oil pressure when cranking to allow the fuel pump to work. The ECM primes the engine with fuel - engine starts and switch closes allowing engine to keep running. Squirt some gas in the intake and see if it starts and runs for awhile. Remember, simple things keep cars from running usually!

IROCmenace

iTrader: (1)

http://austinthirdgen.org/mkportal/m...ine_wiring.gif

To start the process in making sure the computer is sending an injector pulse test at the ECM. Looks like D15 and D16 ground the injectors; the power comes from the fuse box.

I would not use a test light on the ECM itself. It may be old enough technology it doesn't matter but according to the MECP (stereo install cert) you should use a Digi Volt Meter. You may not see the full pulse voltage but it should still go up and down. Make sure you touch something to make sure you have no static electricity before touching the ECM.

This way you will know that the VATS, ICM and everything is working and the computer is sending the signal. If it is start looking for wiring issues all the way to the fuse box. If it is not you know you have other issues.

palerider

To all those great folks that helped me through this ordeal "Thank You very much"!!!
We finally got a running (IROC-Z) today. We labored all day with the last inputs from ASE doc, utilityguy2, IROCmenace.
We did the 3 test I mentioned and on test 2 where we pulled all the injector harnesses to check injector OHMS and checking the injectors by applying 12 volts to them directly, we heard all 8 click. Replaced all connectors. tryed it and the engine tryed. We sprayed ether it tryed. We checked the coil for pip(12v+) white wire had good pulse. Checked the pink wire had volts, but still crank /no start. We then checked the pink/white wire from the coil to the ECM , we had voltage. At that point we pulled our 2 week old Cardone ECM , took it back for an exchange. Installed it and immediately it ran with gusto!!! We still have some problems to work out. The check engine light will not go off, idle is 1500rpm with the needle all the way backed out. I did re-time it with the bypass disconnected, but that idle will not go down was doing this before we started this saga. Can you believe it says to time it in drive! Get runover. Not over yet. Thanks again!!! Also any suggestions on our remaining problems are welcome.

IROCmenace

iTrader: (1)

that is great news! As far as other issues; check your code first. Then do the IAC adjustment process in the tech articles. Do a vacuum test. Unmetered air (vacuum leak) in the plenum can cause high idle/running issues.

palerider

I did a IAC check /no change
I have did the spray something volitile around the plenum and all/no change and nothing to indicate a VACCUUM LEAK
wHEN i GET THE STEERING WHEEL BACK ON i AM JUST GONNA DRIVE IT TO SCHUCKS AND USE THEIR obdi READOUT FOR ANY TROUBLE IF THE mil LIGHT HAS NOT GONE OF.'One other thing==What do you consider a good source of maniform in the maniform to use as a good vacuum source. Thank you IROCmenace

ASE doc

Another "new in the box" part failure. Glad to see it had a happy ending. No need for a code reader on OBDI GM. Jump pins A&B of the ALDL(top right corner of the connector). The CEL will flash codes. Long flashes are tens, short flashes are ones.

A scan tool with datastream and bi directional functions is useful for diagnosis. The Snap On MT2500, or "brick" as it's commonly known, is cheap on craigslist. I paid $2,500 for mine back in the day, now you can buy the same machine for $250 on craigslist. It's a very good scan tool for GM OBDI. Be sure if you buy one that it comes with the GM1 adapter and power cable. I just bought the latest Snap On Solus Ultra w/european. It even works with the OBDI adapters from the brick on early systems. I still keep the brick in my bottom drawer. I used it twice last week and Ill never sell it. Sometimes the old stuff just works better.

IROCmenace

iTrader: (1)

As long as you check the vacuum on an unobstructed line (not ported or filterted) the vacuum reading should be the same. I usually use the ports on the pass rear of the plenum. Generally the one that is not for the fuel pressure regulator.

ASE doc

I agree. One point I will add is, if your car is speed density, avoid tee-ing into the line to the MAP sensor. The MAP needs its own separate vacuum source.

z28m8

ive got a problem for you guys as its driving me maaaddd,
ive got a spark at the coil king lead but not at the plugs,, tried another coil,dizzy and leads from a friends iroc that i drove in my garage,so i know they work,
ive got a '91 z28 383ci that dont go,,
HELP ME PLEASE!!!!!!!!!!!!!!!!!!!!

IROCmenace

iTrader: (1)

If I understand you correctly you have power to the cap with the coil wire but no power at the plug wires?

Did you reuse your cap and rotor on the borrowed dizzy or did you use your friends setup from cap down?

If you have used your friends cap and rotor it sounds like a grounding issue if it is not working with two different dizzy's.

If you used your cap and rotor on his dizzy then you should check your rotor and dizzy contacts, also check the point in the center of the dizzy that contacts the rotor in the center to make sure it is not burned out.

Have you check the grounds on the back of the heads?

Did you try your dizzy, cap and rotor in your friends car?

z28m8

hey ya, tried his dizzy and another cap as 1st new one ,centre terminal broke,
i havent tried mine on his to be honest, but took his off mine replaced it on his car and it started, so?????
earths are on head,firewall,body,coil and dizzy clamp, all continuity checks out, ive got 12v at coil but when cranks over drops to bout 8v??

IROCmenace

iTrader: (1)

You post is a little confusing, sorry. What do you mean the center post broke?

So you tried his in your car and still no start. Try his coil. Are you running an ignition box?

z28m8

the carbon brush that goes to the rotor, cracked and shot out when we were testing continuity on it,, thought we fount the problem, bought another cap,,,,,,still no spark to plugs......
tried his dizzy,coil and amp on dizzy plate and another set of leads.. its a medium spark if i put a plug on dizzy end of king lead,

z28m8

is it correct that i would have about 8v to the coil while cranking, coz the spark has to jump about 4mm from rotor to lead posts, have checked other dizzy/rotor thats same,,,, seems a big gap to me??? i have also hard wired the coil to another battery, ,,,same

IROCmenace

iTrader: (1)

If your friends dizzy, alternator and coil still would not star tyour car I would think you have other problems. Probably best to start a new thread and list all you the mods you have on the car.

ASE doc

If you have spark at the coil and not at the plugs, you need to first verify that the rotor is not grounding to the dist shaft (this is not uncommon) and the cap is not carbon tracked. Easiest to try a known good cap and rotor. If a different cap and rotor makes no difference, verify spark KV at the coil using a cheap adjustable spark
tester($10 at the parts store). Set it at 40K. The HEI should easily jump the gap. If it doesn't, try a different coil wire. Still no good? Replace the coil.
If the coil produces 40K and a known good cap and rotor doesn't produce spark at the plugs, check the plug wires for arcing to ground or internal failure.
Generally, if the wires are more than 100K miles old, replace them anyway and be sure the plugs are not fouled and are gapped correctly. If the plugs are fouled or their electrodes are worn, replace the plugs.
The B+ (pink wire) voltage at the coil has nothing to do with the gap between the rotor and cap contacts. 8V isn't great but it shouldn't prevent the coil from firing. The cause of low voltage at the coil B+ is going to be poor connections at the battery, poor connection from the batt- to the engine block, low battery charge, high resistance in a fuse link, wiring, or poor connections elsewhere in the circuit. You need a good wiring diagram and a voltmeter to test for voltage drop from the battery to the coil and then across each segment of the circuit.

We spent a good deal of time working with the OP of this thread and there is a wealth of information here for future solution seekers. Redirecting this thread to a different car with a different set of issues will only create confusion. Please do start your own thread.