I'm having some issues with getting my 88Gt V6 to run properly I had to disassemble my engine to replace my lower intake gaskets and during the reassemble I installed brand new Tomco injectors. During the reassembly I had to remove the distributor so I took care to replace it in order to be as close as possible to it's original timing.

I went to start it and it fired right up but acted like it was only running on 4 of the 6 cylinders. I have checked all the plug wires and they all have spark going through them and the engine runs consistently at about 1000 RPM but it's very rough. I know it needs more timing work but since it's not firing on all 6 cylinders it's seems impossible to make it run better with just adjusting the timing.

My question is: since the Tomco injectors are a bit shorter then the original Fiero injectors could that cause the spray pattern to be blocked in any way not allowing the cylinder to fire properly?

I have since pulled the rail out again and reinstalled it again using as much force as I could with out damaging anything but enough to try and seat the injectors as well and as deep as possible but it didn't change anything. Any help would be much appreciated. Thanks

Daniel

I feel I should mention that I had the timing light (induction type) out because I was going to time it and I checked every wire and they were all transmitting a spark. I however didn't change any of the spark plugs but did remove them twice to check to make sure they weren't in bad shape and properly set the gap to .045". The plugs are newish from last summer and they are R42TS plugs.

The Tomco injectors should work just fine. I used to have some before I switched to Accel injectors in my new engine.
Here is a picture of them side by side. You can see that the o-rings are in the same location overall.

You just need to lock them into the fuel rail, lube the o-rings, and pop them into the lower plenum. There is no need to use a lot of force.

[This message has been edited by avengador1 (edited 03-21-2008).]

So unless the injectors are faulty or the wiring is faulty there should be no problem with injectors?

I don't know what else to check that would make the engine run so roughly. If my engine is getting fuel and it's getting spark what other cause would allow the engine to run on less then all cylinders.

When trying to time the engine after I let it warm up I tried the shorting of the Ground and Diagnostic terminals but it wouldn't even start after that would that indicate my timings is way off?

[This message has been edited by The Poopsmith (edited 03-21-2008).]

You may have to start from scratch and set the timing from #1 TDC just to make sure. I mean, if there are no obvious loose or broken wires..... Of course, you have verified the spark plug wires are in the correct order?

I ask because I just tried to set lash on the #6 cylinder when I should have been on the #1. Sometimes it's the simplest things.

I guess I should clarify if I'm NOT in diagnostic mode it will run but it runs like it's missing 2 cylinders but if I put it in diagnostic mode it will not start at all. I not certain the timing is way off unless it's drastically changed by shorting the A and B terminals I am sure that something isn't in sync but I don't know what to check that I haven't checked yet. I'm just trying to get it to the point where it runs on all cylinders again. It's not throwing any codes either.

Diagnostic mode does drastically change the timing. It pulls all the lead that the ECM adds, like 30* of advance to the base timing of 10*. That is why I suggested going back to basics just to eliminate timing as an issue. Just a suggestion.

That's something I will definitely try then. Thanks

When a distributor is removed mark it with white paint where it connects to the block,remove the cap and make a mental picture of the rotor position as you pull up and as the gear clears,,best to pencil mark the "pre removal" point to assure proper reinstall..
remove intake hose and with engine running squirt a small amount of quick start in intake ,, or before you start engine spray a small amount of quick start into intake any degree of smoother running would indicate an injector problem.. probably wireing this is best done with the assist of a helper
Eyeball dist post to make sure none have gotten bent ,never ajust these unless positive they were bent
Look up a recent post on the new cardone rebuilt distributor a wealth of timing info...use the inductive time light on the central coil ... it will be 6 7 pages back distributor replacement tips ??................. by jetman excellent

[This message has been edited by uhlanstan (edited 03-22-2008).]

What causes the injectors to fire is their something I can or need to adjust to sync them up with the rest of the engine?

[This message has been edited by The Poopsmith (edited 03-22-2008).]

Since you removed the distributor, I'm guessing it didn't install exactly in the same position it was at originally. You would have had to match the base of the distributor and the rotor position to exactly where they were before you removed it. Try setting your engine to TDC, as suggested above, and reinstall the distributor with the rotor is pointing to the number 1 post of the distributor. This should get you close enough to be able to set the timing once the engine is running.

Does the ECM control the fuel injectors?

Happy easter!

If I wanted to check my injectors just to make sure they were receiving or are able to receive an electrical signal is there a way I can do that?

[This message has been edited by The Poopsmith (edited 03-23-2008).]

YES ,,CHECK IT WITH A NOID LIGHT do you have a manual?? of course the manuals do not have this info.. look this up on the forum ,, a voltmeter can be used to check injector timing check the forum for info I doubt if this is the problem it is out of time or the wires on one or 2 of the injectors have been loosen or disconnect in some manner..if it ran O K before you worked on it it is a timing or loose wire problem.. make sure plug wires do not parrallel each other and touch each other for a distance even if new

The fuel injection system is controled by the E C M,, the injection system can be dificult to diagnose you want to determine if the injectore are firing at the proper time the noid light is the simplest method ,normally if you have an injection problem it is real simple or druid chanting is requiered for understanding how the ecm, the prom and the wires cause this to,happen you MUST achieve proper ignition timing before you move to druid chants, noid units agarage installing a water pump should be able to achieve proper timming of a car that runs for a low price if this is a trusted service center you have used before.a serious injector problem requires experience. first check the simple connections ect..
Even the most experienced motor heads often have a garage they use for some work,, My personal mechanic works 9 hours a day in a filthy garage but he has many many years experience and I do not ask the price .I trust him

[This message has been edited by uhlanstan (edited 03-23-2008).]

I did some research on injector timing and am I correct in assuming that since I completely removed the distributor and replaced it where I wanted it to be that I could have gotten the injector firing sequence and spark timing sequence out of sync? If this is so how do I resync the two? Thanks

Daniel

The injectors are "fired" by the ECM by grounding them inside the ECM (IIRC called Injector Drivers). Injector firing is controlled by the fuel/spark table written onto the ECM's prom (aka computer chip). And in our cars (even though injectors 1,3,5 and 2,4,6 are wired separately) all 6 injectors fire at the same time. The fuel just sits at the back of the valve until it opens. That is why we have multi-port fuel injection as opposed to Sequential Fuel Injection which fires each injector as the intake valve opens for that cylinder.

So what does all this mean? It means that once you have your ignition timing set then all the rest will happen in the proper sequence. Have you manually reset the timing to 10* at #1 TDC yet?

quote Originally posted by Hudini: The injectors are "fired" by the ECM by grounding them inside the ECM (IIRC called Injector Drivers). Injector firing is controlled by the fuel/spark table written onto the ECM's prom (aka computer chip). And in our cars (even though injectors 1,3,5 and 2,4,6 are wired separately) all 6 injectors fire at the same time. The fuel just sits at the back of the valve until it opens. That is why we have multi-port fuel injection as opposed to Sequential Fuel Injection which fires each injector as the intake valve opens for that cylinder. So what does all this mean? It means that once you have your ignition timing set then all the rest will happen in the proper sequence. Have you manually reset the timing to 10* at #1 TDC yet?

I haven't been able to work on my car yet so I'm just asking as many questions as I can until I get the chance to. I feel the more I understand about the fuel delivery and ignition system the better I will be able to deduce the problem. Thanks

quote Originally posted by The Poopsmith: I did some research on injector timing and am I correct in assuming that since I completely removed the distributor and replaced it where I wanted it to be that I could have gotten the injector firing sequence and spark timing sequence out of sync? If this is so how do I resync the two? Thanks Daniel

for the most part - there actually is no "injector sequence" - the ECM fires 3 at a time, twice per revolution, and has NO IDEA where TDC #1 is. every time you start your car - it will be different. - basicly 1 of 3 patterns will happen. it does time them to the igntion pulses - but it has no clue as to which ignition pulse is #1.

this is the difference between MPFI & SFI
Multi Port Fuel Injection - fires injectors on multiple ports at a time
Sequential Fuel Injection - fires singly

Thanks to everybody whom responded I learned so much about my Fiero through your replies.

I finally got it running properly and no damage was done but I made a newb mistake. During my first ever attempt at adjusting valve lash I torqued one down a bit too tight on the exhaust side and therefore had no compression on one cylinder. Fixed that and it ran like a champ. Thanks again.