pgoldston

Im new to the site but I have been lurking for sometime. I have recently picked up a 1989 camaro iroz, 305 a4. Having a couple of issues that have me stumped. I have searched here and just havent seen something that caught my eye as the same issue. So here the break down

The car if its cold will crank with spark and fuel pressure but wont start. Spray some starting fluid in it and it will fire up. Once the car warms up if I go inside of a store and come out the car will fire right up most of the time. BUT if I kill the car turn the key back for anything less than a minute or so it wont restart with out the help of starting fluid. If I wait for a minute or so it will restart most of the time.

Here is what I have checked.
Set base timing to 6 degrees with the connector disconnected
reset the TPS voltage
reset the IAC
Test fuel pressure 42-45 with vacuum unhooked. And it fluctuates properly with the throttle.

Pulled the ECM to look at the numbers. Looks like someone has been in it but I cant confirm. So here is what is in the car

ECM is 01227165
PROM apym 3493

I have double checked to make sure this wasnt a phanton cold start injector car. Theres no boss on the intake for the injector, no wiring, no rail for it. Build date is 09/88

I hope I have provided enough information and data for you guys. I really enjoy this car and would love for it to just start up regularly. IF there is anything else you need just let me know. Thanks for the help

Patrick

ASE doc

Do you have access to a scanner. Data may show you whats causing this problem. You say you reset TPS so I assume its at .5 volts at closed throttle. MAP voltage should be close to 5v when cranking. We need to verify these things as the ECM sees them. In a pinch you can test voltages by backprobing at the ECM connector but nothing gives us a better window into the ECM than a scanner.

Check injector pulse by testing for signal and power at the injector circuits in the ECM connector. Use a test light to back probe pin D15(blk/pnk) and D16(blk/lt.grn). They should show power with key on and flash the light when cranking.

Injector impedance can be checked by testing between these same terminals and the injector fuses at the fuse panel. Unplug the ECM and look for 3-4 ohms on each circuit. Less than 3 ohms means a bad injector or circuit. Does it idle okay cold? Or do you have to keep it running with the throttle for a while after starting?

pgoldston

It idles fine when cold. I will check the other items what I get a chance.

When you say 3 ohms on the d15 and d16 Im guessing one probe on the D15/16 terminal and the other on a ground spot?

Thanks again

ASE doc

No, Im sorry for the confusion. One probe on D15, one probe on the Inj 1 fuse. Then, one probe on D16 one probe on INJ 2 fuse. Test with the key off, ECM disconnected.

It seems as if the injectors arent functioning until the engine is actually running. Its strange that once ytou have it warmed up it will restart. Im thinking injector circuits.

This is an odd problem. The kind I love to get at work. It will be interesting to see what is causing this.

Are you able to find a scanner?

pgoldston

A buddy is suppose to have one for the car. When the car is cranking what do you suggest that I log and what to look for.

Is there any chance that a ignition module or a pickup is bad in the dizzy. I have read some thread saying something about the ignition module controls the injectors until 300+ rpm. Not familier with the chevy setups. Thanks for the help ASE. got to must some work in on my turbo mustang tonight but will try to get some data for you. Thanks again.

ASE doc

The ignition module provides a "pip" (primary ignition pulse) to the ECM. The ECM uses this signal to time injector pulse and EST. So actually the ign mod controls the injectors all the time. What happens below 300rpm is that EST is bypassed so that spark timing is fully retarded for start up. When engine speed exceeds 300 rpm, the ECM takes over ignition timing.

I have concerns about your injector pulse. This is why I want you to test for it. Several things can cause a loss of injector drive. Among them are TPS voltage. If TPS is above 4v, the ECM goes into clear flood and shuts down injector pulse. Low MAP voltage can cause injector on time to be decreased. Not providing sufficient fuel for start up.

Therefore, I want to know what TPS voltage and MAP voltage are on datastream. Also what rpm is during cranking. Need to verify that the ECM is receiving pip when cranking. Checking these items on datastream tells us what the ECM is seeing. If we see data that points to a problem, we can then pinpoint that issue. This saves us alot of guessing.

pgoldston

okie doke. Suppose to get the hardware tomorrow to datalog it. As soon as I get time info I will post up and try to do some screen shots. Thanks for all the help!

pgoldston

here is what we found out

all injectors tested 17.5-17.9 ohms at the injector

both injector fuse are good

d15/16 circuits 12v and hot with key on, 13.x V while running with changes in voltage.

d15/16 circuit tested at 4.7 ohm unplugged from the ECU to the fuses.

TPS is at.5v

MAP where the hell is it? from wha tI looked up its on passenger side near the accumulator. I looked all over traced vacuum lines and could not find it. I have a pinout of the ECU connectors and could not find the MAP refrence wire on that. If you can tell me what pin at the ECU is the MAP I will check it. Hope this gives some direction. I will have the scanner tomorrow.
Thank patrick

ASE doc

Excuse me. I assumed that being an 89, your car was speed density, meaning that it uses a MAP sensor and no MAF sensor. Does it have a MAF sensor?

ASE doc

Your injectors and circuits appear to be okay. Perform the injector pulse test I explained above. If you have a noid light and can get to an injector connector, you want to test at an injector also.

I an really leaning towards this being an ignition module failure. We want to verify that there is no injector signal when cranking and that there is signal with the engine running. It could possibly be EST also but since you already tried swapping ECMs I think its probably the ign module itself.

pgoldston

ok well this car must be a ghost so to speak.

The car is a MAF setup. But this is how it came from the factory I got the car from a one owner. All the wiring looks good and factory. Seems to be odd. The computer has had someones hands on it at one time. one of the screws to the prom cover is missing. I got the scanner and will look tonight at it.

With the EST when I unplus the bypass connector to set the timing I can set it to 6, while watching the timing light I can have someone plug it back in and it will advance and move around like it should.

the distributor does look new. I almost pulled the ignition modual last night thinking it could be that. as soon as I scan it I will let you know.

pgoldston

ok well I got the scanner on it today. this thing looks like a nintendo.

at first I couldnt get it to find the MAF had to change the settings to a 1988 camaro. Finally I was able to get it to find the maf.

Everything seems to check out. The MAF was reading correctly, all the sensors seemed to working correctly.

I put my fluke 87 on the injector.

intial key forward, but not to start no voltage.
key turned to crank and there is voltage but no start.
Starter fluid car running and injectors firing fine on the meter.


So 1989 was speed density and this car is a MAF. Build date is 09/88. Is this some how a really late 88, with a 89 compter or something. Again this doesnt have a cold start injector on it or the boss on the intake runner.

The computer is for 86-89 and the prom is specifically for a 89. yet again its MAF. So Im really lost on how to fix it. Does it need a 88 prom, if so then how do I fix the cold start issue.

Hope this helps out, the more I dig into this car the more its a unicorn

ASE doc

No unicorn, just an early build date. I dont know if prom's going to help. Fluke 87, is that a graphing meter? Or just a digital. Would be great to look at injector pulse on a scope.

There are many things that might cause this problem. Weve verified fuel pressure while cranking. We know that TPS is at .5 while cranking. We know its a MAF car with no cold start injector. Actually, no cold start injector might cause a long crank and hard start but shouldnt cause no start. One thing to try would be to unplug the MAF and try to start it. MAF may be screwing with cranking injector pulse.

Another thing is coolant temp sensor and/or inlet air temp sensor. Check these values on data.

John 89 Formula

89 was the last year for maf, 90 was the first year for speed density.

ASE doc

Thanks for clarifying that John. I wasnt sure of the year it changed and hadnt looked it up yet.

pgoldston

I will try unpluging the the MAF and try the start.

the Coolant and the intake temps check out. They were with in range and were moving accordingly.

the thing that gets me is the injectors dont get an intial when the key is turned forward. I dont know on the camaros but on other models when the key is intially turned forward injectors get a slight pulsewidth to help with starting.

Could it be a voltage issue by chance? the car cranks just fine and spins but Im wondering if the battery doesnt have enough cranking amps. I noticed that the battery drops to 10.2 volts during cranking. I have a battery charger Im going to through on the car and see if I can get the volts up during charging to see if it will help with it. Just wondering if the spark is to weak while the starter is turning over.

ASE doc

Thats possible. At this point I would look closely at anything that doesnt seem right. As far as injector pulse goes, there should be 12v at the injector with key on. Pulse wont begin until the ECM sees PIP. The fuel pump is what you might be thinking of. It gets energized for 2 seconds when key is turned on.

I would be checking actual injector pulse waveform at this point. This engine uses a pulse-hold injector drive pattern. A healthy injector pulse has a particular waveform. I would try to describe it but its really best to see a picture of it. www.picoauto.com/tutorials/fuel-injection.html has a good picture of a healthy waveform. You need a labscope to test yours, then compare what you see to this sample. Post your observations here.

John 89 Formula

Just for giiggles, check the red wire that comes off the pos+ battery cable there is a 20 amp fuse on it, make sure the fuse is in tight and the wire is good condition. On one of my cars that wire was rotted almost to the point that it was broken, it caused all sorts of problems.

P.S. it is the main 12v supply for the fuel pump, ecm, maf, and a few other things.

1989IROC-Z5.7L

iTrader: (2)

Injectors most likely.

ASE doc

#18 good call, #19 youre probably right on. Scope pattern of the injector pulse will show any type of injector failure, whether its a coil or stuck pintle.

pgoldston

The injectors are new. I dont have access to a ocsilloscope so I wont be able to check the waveform of them.

Its just so odd that the car will run fine. it doesnt miss or stumble off idle or tip in. as well if the car sits for say 10 minutes after warm it fires right up. but if you kill it and try to restart it , no go. As well if its cold it wont start. Theres spark at the coil, spark at the plug. the fuel injectors all have power. never run into an issue where it has spark and fuel, and the car runs just fine but wont restart.

Im completely baffeled

pgoldston

oh is the fuel pressure suppose to bleed down after it shuts off??

1989IROC-Z5.7L

iTrader: (2)

It will bleed off, slowly.

What brand injectors? Hopefully their not accel!

pgoldston

they look like a factory replacement. I dont know what they are exactly

1989IROC-Z5.7L

iTrader: (2)

I installed new Accel injectors, they done the same as yours is now. Checked everything, finally bought new SVO injectors fixed the problem!

ASE doc

The injectors may very well be your problem. I wasnt aware that they had been replaced. That may be cause for concern. However, before we spend alot of your money, I am not one for replacing parts without proving that they are bad. At this point there is still too much we dont know. I cannot state with any confidence that the problem is in fact your injectors. Scoping injector signal would have told us alot. Im sorry you couldnt do that. Well just have to work with what we do have.

There are a few more things we can look at. On datastream, with the engine running, we need to see what block learn and integrator are doing. Neutral for both is 128. Higher indicates a lean condition, lower indicates rich condition. While cranking, look at injector pulsewidth. It should go high while cranking, then decrease incrementally as the motor goes through after start enrichment and on to warm up. Also actually listen for the injectors to "click" steadily while cranking. You can use a stethiscope or even just a long screwdriver with the butt of the handle to your ear.

Obviously your motor is not getting enough fuel to start. We know that fuel pressure and sensor inputs are all okay. Looking at block learn and inegrator will tell us if your injectors may be faulty or mismatched to the engine. Or if some other issue might be causing a rich or lean condition, which may be affecting start up. A good idle doesnt point to bad injectors or any gross rich or lean condition. But we need to know this. We need to verify that the ECM is actually commanding crank fuel pulse(long pulse width) before we condemn your injectors.

pgoldston

The scan tool that I used this week for some reason would not pull up pulse width to log. so Im going to have to find another to log that. I am thinking that it is not commending a start up puslewidth.

ASE doc

Thats my thought too. Doesnt make sense that injectors that run well, especially idle well, would cause the engine not to start. However, I never say never. After 35 years as a tech, 28 years on FI, Ive learned not to get too stuck on any idea. Cause I could be proven wrong. One quick check, no scanner needed, would be to sonic check the injectors. Just use a screwdriver like I said above and, while someone else cranks the motor, listen to an injector. It should click notably.

pgoldston

I will check that over the weekend. Been tinkering on to many cars this week. If I dont give the wife some time she may burn the place down.

ASE doc

LOL. Yeah dont neglect "the other woman". JK

pgoldston

ok so it seems we may be onto something.

I listened to the injectors while it was running fine and you could hear a hard pintle noise. Very very crisp. We killed the car and tried to restart it and I could hear some noise but it was really really faint but right as the key roll back right as the starter stopped I could one or two hard pintle clicks. So it sounds like the computer is trying to command the fuel but maybe its not getting enough voltage to it. The noise I was hearing may not be injector like I said it was really faint. So it computer maybe not commanding it. But for sure when the key somes back and right as the started starts to die the inejctors kick in for a click.

it just hit me that to rule out the ignition switch I could have run aremote start wire to the starter that way the voltage wouldnt get pulled just to see what it would do.

Any ideas on the next step.

Patrick

Chevy86 IROC-Z

iTrader: (17)

Didnt the ninth injector (cold start) get deleted for the 89 year?

ASE doc

I think the cold start injector did get deleted for 89. Ive looked at the factory diagrams this last week and there was no cold start injector on the 89.

The loss of injector pulse while cranking really sounds alot like a poor ECM ground or power supply issue. The ignition switch could cause this also. You did say you had spark when its not starting right? The same circuit from the ign sw feeds both the injectors and the ignition coil. Its the pink wire.

If there is a poor power supply to the ECM, it may not get enough voltage during cranking when battery voltage is pulled low by the starter. Once the motor starts, the alternator boosts system voltage to about 14v. This can overcome a poor supply.

I have seen similar issues that were also very hard to find. The way Ive found them was to watch voltage at the ECM batt+ and ign inputs while cranking. Watch for the voltage to drop below 10v. Does it drop below 10v on all inputs? Check batt connections and connections at starter along with engine grounds. Did voltage drop at only the ign input? Test for volt drop across the ign sw. Run jumper wires from the battery to all 12v inputs at ECM. Follow your factory diagram and take care not to put 12v to a ground or sensor circuit.

When your engine starts fine with the jumpers connected, check all power and ign circuits to the ECM. Recheck grounds.

Chevy86 IROC-Z

iTrader: (17)

. Even if there was bad voltage while cranking, there may be a drop in the strength of the spark, but even if there was a 2 volt drop (from the normal 12 volt), you should still be left with a solid 10 volts to the ignition system. With 12 volts, the dizzy supplies the spark plug with a range of 45,000 volts on a stock ignition system. So with the loss of 2 volts, the spark at the spark plug would still be around 41,430 volts which I believe that it is more than enough power to generate a hot enough spark during cranking. I would definetly plug plug # 1, hold it close to ground (cars body), then crank. If you see a consistant solid blue spark with every revolution of the engine, then you definetaly got spark. You may have a timing issue. There are a lot of possibilities, but I would focus on the ingition system because your obviously getting fuel. Get a test light and hook it up inline with a injector wire, then crank and see if the light pulses. If working properly, it'll pulse while cranking. Do the test on both sides. Have you done a complete tune up of the TPI system? Check out these sites.

1. http://webcache.googleusercontent.co...&ct=clnk&gl=us

2. http://mpikas.blogspot.com/2008/08/t...june-2000.html

ASE doc

The car starts with starting fluid so we know that its got spark. Were looking for a cause for the ECM not firing injectors during cranking. The ingition coil will fire with under 10 volts. It is not digital like the ECM is and can work on a much wider range of voltages. The ECM does have a voltage regulator built in that can regulate anything from 10-17 volts. Outside that range, the ECM may not function well.

Remember that when cranking, the ECM only needs to provide a 5 volt signal to the ign module, placing it in bypass or crank retard. The ECM has to fire a quad driver to create injector pulse. This takes alot more power.

Chevy86 IROC-Z

iTrader: (17)

When you crank the engine, does it turn over fast, or does it suffer like its stuggling to turn over. If it struggles, then the battery may not have enough cranking power (amps) to turn the engine over, or the starter may be going bad. Just a shot in the dark.

ASE doc

Those are very good points. That would go along with a low voltage issue.

Chevy86 IROC-Z

iTrader: (17)

Now that I think of it, it does huh.

87CamaroLT43

I actually have the same problem with my 92 formula... except I get no injector pulses on start up. I have managed to get the car running by grounding the low side of the injectors, allowing the engine to get fuel, but after in runs For 3 seconds going over the 400 rpm threshold it stalls and dies immediately... I have changed the dizzy, ignition module, map sensor, ohmed the injectors, checked for power or grounds issues.. Is it possible that the injector driver in the ecm fried?

RacerX13

This sounds similar to the problem I had on my car. It would not always send power to the fuel pump after it was warmed up. I didn't have the benefit of a scanner or data logging equipment and went thru the process of replacing all the components that are tied to the fuel pump circuit-FP relay, MAF relay, oil pressure switch, ect., replaced the ignition module, lots of wire tracing and checking connectors. I did find out by accident that if I grounded the pins on the ALDL to put it into diagnostic mode it would send power to the pump and start right up when it was having this problem. I swapped in another ECM with my original memcal and it never did it again.

Chevy86 IROC-Z

iTrader: (17)

You can get a Reman ECM from Kragens or Autozone for around $76 with the core exchange.