hoss1059

I'm having trouble keeping the timing in my son's 1988 Formula 305 TB. I unplug the ECM connector and set the timing. As soon as I plug the ECM connector back together it runs like crap and timing goes eskew. If you look at the timing marks while the ECM connector is plugged in, it jumps across the board. What could be causing this? Bad knock sensor? ECM?

sqzbox

I have the exact same car! I assume you are disconnecting the EST connetor with the engine off and after timing it, re-connecting it with the engine off also. I don't know why you would be looking at the timing marks afer re-connecting because it's not going to be anywhere near where you set it with it connected.
When you say it jumps across the board, does that mean it's moving back and forth eraticly or just off the scale ? You might be having issues with your dist. being worn or a module going bad. Auto Zone will test the module for free if you take it in to them.

hoss1059

Yes, I'm disconnecting the EST connector. Only reason I looked is because after it is reconnected, it starts misfiring badly. Back firing up through the intake, etc. With the EST connect disconnected it idles and runs fine until I shut off the engine, re-connect, and restart. The original ignition module was bad (would get hot and not allow the car to start back up) so I just replaced it and had this problem pop up. Didn't know if maybe the knock sensor was bad and messing with the timing for some reason but never heard of it doing this.
Little history, guy that owned the car before tried to "soup" it up by putting a carb on it and butchered the engine. I got all the original parts and put them back on along with new fuel lines, vaccum, etc. Dropped in the dist and got it pointed to #1, etc.
My son can drive it to town and back with the connector undone but it still gets stupid and back fires or whatever on occasion up through the intake.
Thanks,
Tony

sqzbox

Let's backtrack a little. How did it run before the no start problem after it got warm? Where and what brand module did you get? Usually, if you go back to the last thing you did before the problem started, that will put you on the right track.
When I bought my form. from my daughter-in-law they had it in two different "shops" and it was running like crap with no power and dieing everywhere it went. It turns out that both of the so called "shops" had set the timing with the EST connected. When I disconnected it, it was running 25* retarded. After I reset the timing, it felt like a new engine.
With the EST unpluged your running at what,4* across the board with no advance at all. At say 2000 rpm your spark is hitting kind of late and might explain the backfiring. I would recheck the position of the rotor button at TDC and if all looks good, get the module checked. Bad modules over the counter have been known to happen.

hoss1059

We had timing issues prior to replacing the ig module and had awaited for me to get my timing light off of ebay to play with it (I have a 2k T/A which obviously doesn't even have a distributor so I haven't needed a timing light). I might take the ig module back out and take it back down to AZ and have them test this one out. It's an AC Delco from AZ. Rechecked the rotor and it is at TDC, no doubt. I had an 88 IROC Z years ago with a 350 TPI that we suped up and we always set the timing the same way as my sons car, by unplugging the EST connector and never had any issues.
Thanks again,
Tony

sqzbox

Have you checked for any codes? I've never had any problems with backfiring through the intake with my car. It does sound like an ign. problem though almost like spark jump between the cables or something. I did have a problem with the wires going to the external coil once, and it caused the engine to miss and would kill my tachometer. I found it by accident while moving wires around in the dark while checking for arking and got my finger between the wires. Believe me, I felt it before I saw it! After separating them the problem went away.
If your knock sensor was the problem, I think all it would do is retard the spark advance trying to stop the ping or knock. Backfiring throught he intake useually means spark is catching an intake valve open. Wish I could be more help but it's like a doctor diagnosing an illness over the phone. Good luck!

hoss1059

Sorry to bug ya again. You said you have the same exact car. What does this plug into? Like I said, guy that owned the car tried to carb it and butchered the car. I didn't even have the old air cleaner, had to get one for a 91 camaro off of ebay. I looked at the electrical schematic in my Haynes book and couldn't find anything. Well the same schematic says there are 7 wires that go to my distributor but in reality there is only 6 so I can't trust it anyway. Any help would be greatly appreciated cause I don't have anything in the area this would plug into.
Tony

ShiftyCapone

iTrader: (7)

If you are afraid that the harness has been hacked you may want to get a harness out of a junk yard and go from there. It should cost next to nothing and you will be assured that there isn't any funny stuff going on. The EST is behind the passenger side strut mount. You may want to varify that you unplugged the correct thing.

hoss1059

No. the harness is still fine and OEM just like the day it was rolled off the line. Just don't know what this particular connector goes to. I'm familiar with the EST connector which is up and to the left of this connector I showed in the pic. My ESt is the same brown colored wire as yours. I know it doesn't go to the distributor. The original air cleaner had a sensor in it so when I replaced the air cleaner assembly with this one off of ebay, I bought a new sensor and have a plug going to it. Just have this one left and don't know what it does to. Checked my timing again against TDP on the compression stroke of #1. Rotor is pointing dead at it. Driving me nuts. Unplug EST connector runs fine. Kill it, plug in the EST connector, start it, runs like crap.
Thanks,
T

sqzbox

That connector plugs into the EGR control solinoid. The EGR solinoid (that I don't see in your pic) is a small elect. vaccum control that should be where you have the T fitting going to the EGR valve. It has two black plastic lines going to it. One from manifold vaccum and one to the EGR valve on one end, and the plug you have pluging into the other end. When the engine goes into closed loop (about 190*) the computer will allow vaccum to the EGR valve off idle. It should close at idle and deceleration. Sorry for the slow responce but the comp. has been down due to heavy rain in the past few day's!

hoss1059

Thanks so much for emailing me back. Had a friend of mine come over this afternoon and we finally figured that out. Got one on order from OReilly's as we speak. Plus we went back over my complete vacuum setup since I had to redo it from scratch after the previous owner butchered it up and think we have it pretty much figure out now. My Haynes manual is lacking to say the least. The engine electrical schematic doesn't even show the EGR solenoid, it shows everything else except that one sensor! Go figure. I've replaced just about all the sensors that were either missing or damaged because of the pevious owner so hopefully this should be the last one (knock on wood).
Thanks again,
Tony

sqzbox

Hey, no problem! Glad to be of some help. That's why we have TG.O and it's helped me alot! E-mail anytime! I'm surprised you weren't getting a code 32 on the missing EGR solinoid (does SES light work?) After you get it together you need to clear the trouble codes from the comp. and start over again. Does the air cleaner you bought have the IAT sensor in it and pluged in? You'll get a code and light right off if it isn't. Part of the drivability problem you were having was caused by the constant vaccum to the EGR at idle and deceleration. IUt might have not been all the problem but I'm sure it was causing rough idle and poor performance. Keep the updates comming! Like to hear that it's running good at some point in the future.

hoss1059

No, when i got the air cleaner it didn't have the sensor but it does now. Yes the check engine light does work but I wasn't getting any code. Thing is it didn't run for very long with the EST connector connected to probably kick out a code. Yes, we figured the same thing one we realized what the sensor was that was missing. Then it made perfect sense. I will see tomorrow afternoon once I get home to play with the new sensor. I'll let you know.
Thanks again,
T

hoss1059

I put on the EGR solenoid and it still runs like crap. Can not get this timing thing figured out. One thing that has me puzzled is in my vaccum diagram it shows a line coming from the air injection valve solenoid but I've looked all over that thing and haven't found a vacuum port yet. You have an A4 so you shouldn't have the air pump like my son's with the M5. Looking to see if anyone has a M5 setup to see if my vacuum setup matches theirs. I'm getting no codes at all with the EST connected. I cleared it and set there rev'ing it at 3 grand or so for five minutes and no codes pop up. Course as soon as I let off the gas it dies.
Sigh..

sqzbox

I don't see how the A-4 and M-5 would be different unless a connection to the injection pump on the M-5 would slow down the closing of the EGR valve during shifting (probably why). Mine goes from the front of the TB to the drivers side port on the solinoid and the passs. side port goes to the EGR valve. How does it run at 3K RPM? Man, it could be a whole basket of things causing it to run crappy. Connections to the computer, fuses, TPS, 02, fuel pressure, worn dist, one guy's car started running like crap recently and it turned out to be the dist. he replaced it and it ran like a champ! Funny though, your not getting any codes Maybe the previous owner had the same problem and that's why he tried to convert to carb. I think that before you burn anymore money on it you might want to take it to a good mech. and have him hook it up. His diagnostic machine will give him real time data and he should be able to figure it out pretty quick plus it will save you some stress and you can get the kid on the road!!

sqzbox

I'm leaving on a vacation to Fla. going to catch a BIG fish hopefully. 2nd son is getting married tomorrow and I'm out of here at 3am sun. See ya on the 8th of Oct. Sqzbox

sqzbox

Yo Hoss! Just got back from Fla. Vacation was too good! Just checking back to see if there's been any GOOD news. While I was in Ft. Walton beach I stoped in a store and got out of the GP to see an 88 Form. (white) just like mine sitting at a light execpt he had a 4" cowl hood and looked 10 yrs. newer. My first reaction was to chase him down and check it out and toss him the 3rd gen web add. but the light turned and he was GONE. Oh well, I wonder how many 88's are still out there?
Toss me a line see how yours is comming. Sqzbox