I've tried to use the search with nothing that I can find that just doesn't quite hit it.

86GT with auto. The car will start and run, barely. W/ a timing light, every fire is in a different degree. Varies about 6 deg each way. It's all over the place. You can put load on it, it varies a little less, but still lacks power and is all over the place. The odd thing to me is that it's really fast. Not like something is adjusting to over compensate, but just crazy. Is the ECM a possibity? I'm going to give that a try.

FYI-Here's what I've done that I know is not the problem:
-timing chain
-distributer
-ignition module and coil
-plugs and wires

Really seems like something that's wiring or computer related, but any input would be appreciated.

------------------
Dana Mitchell
Member of the Gateway Fiero Club
95 Impala SS
95 Roadmaster Estate Wagon
87 GT Maroon w/ Silver Auto
86 SE Red w/ Black 3.2L w/ T-440

When you say you've "done" those items, does that mean you replaced them with known good or new items?

Things that can cause jumpy timing included worn out distributor gear, worn out cam gear, worn out timing chain, bad module, bad pickup coil in distributor, bad rotor (cracked magnetic layer creates extra magnetic poles and causes false triggers).

The ECM controls timing, are you jumping the two proper pins in the ALDL connector before checking timing? Is your idle stable and at 1,000 RPM when you check timing?

The only part you haven't changed in the timing system is the ECM itself, you can try using a known-good ECM.

JazzMan

well, first thing I'd say is
are you jumping the a-b pin on the ALDL connector?
if not, your base timing is way off, and the jumping you are seeing is the ECM controlling the timing

Ok... I know those items are good. I swapped parts off my 87gt just to verify. When I had the timing light on it that was jumping the aldl connector. That's how I can tell how many degrees(roughly) that it's out.

Cam gear was my first suspect after inspecting the timing chain. I've tried to turn the rotor to replicate that much "slack" in the gear lash. It doesn't seem to have that much play.

Beyond the ECM I think I'm about at the stage that I need to pull the motor to check for wear on the back side of the cam.

Thanks guys.

quote Originally posted by Pyrthian: well, first thing I'd say is are you jumping the a-b pin on the ALDL connector? if not, your base timing is way off, and the jumping you are seeing is the ECM controlling the timing

I agree...
Jumping the A and B terminal of the ALDL connector freezes the timing which should then should be set at at 0 deg (I believe) other wise it could be a sloppy timming chain or the dist. needing a shim to tighten up the up and down play in the shaft

------------------

GT just waiting for the conversion

84 Fiero Turbo Vortec 4300 Phantom GT
L35 block, Syclone Intake and ECM with Moates adapter
50lb injectors, 3 bar map sens, T04B H3 Turbo

www.cardomain.com/id/vortecfiero
Murphy's Constant Matter will be damaged in direct proportion to its value
Murphy's Law of Thermodynamics Things get worse under pressure.
Arthur C. Clarke "Any significantly advanced technology is indistinguishable from magic"

sorry to invade on your thread fiero-freak, but I am haveing the same problem. I have 2 question for everybody.
first was your timing mark there or did you turn it to TDC and mark the pulley yourself.
I marked my on the 0 mark I think but when I ran the car and check it the mark was way off. I want to say a good 20 degrees to the left, if you were on the passenger side looking down.

secondly what is the veci average for the 2.5 4cyl.

I havent change anything that goes with the time but if my timing is this far off what should I start with first?

And Again I am sorry for invanding on your thread

So I understand you to say that you pulled the balancer and timing case cover to inspect the chain and related componets?
Are the plug wires new?
Have you swaped distriubtors?

Yes, I have had two distributors that I know are good, both were installed with the same results. There is no vertical play in the distibuter, hold down is tight. While I inspected the timing chain that was only 10K old, I replaced it while I was there, along with the water pump. Metal impeller which had since sucked down 3 thermostats! Short of the cam gear idea, which I should be able to verify with the distributor, but can't, the only other crazy thing I can think of is a broken cam shaft. Broke on an angle so it still turns, but has enough play to cause the misalignment, but that sounds a little far fetched.

I agree, the cam would need to broken at the very front and would have come out when changing the chain in most cases.
It sounds like a timing advance problem even though it should have been disabled when attempting to set the timing.
Take a shot at changing the computer, you have a spare? Just keep isolating componets, it will show up.

[This message has been edited by Indiana_resto_guy (edited 05-11-2006).]

Thanks...I will definately post what the solution was when I find it. I'm going to pick up an ECM tonight and should get to it this weekend.

I've been watching this thread cause I have similar issues. My motor has about 4k miles on it and did not have this problem in the very beginning. It has a coyles true roller timing chain and don't think it could be the problem from stretching, too much slack, valve lift is 473/497. I have changed the ign. module. Had a DUI module that went bad, replaced with a auto zone cheapy. Might be the cause. Maybe the MSD 6AL. Or I might put the stock chip in and see how it does. Haven't checked the distributor yet. Don't know if any of these ideas help but can't hurt.

------------------
85 GT 3.4
Auto 3.08
14.9 @ 90 1.9 60"

It sounds like a timing chain to me. You do not have to pull the timing cover to inspect it for the amount of bouncing you said you get. With that much bounce, just take the harmonic balancer and put both hands on it and turn it one way and then the other. If the chain is worn you will feel a lot of slack. If you feel no slack then the chain is good.

quote Originally posted by ka4nkf: It sounds like a timing chain to me.

Not sure if that was to me or not, but I know it's not my chain since I replaced it right after I started having this issue. There's not even 1K on it.

I did pick up the loaner ECM tonight. I'm going to head over to mess with it tomorrow and see what happens.

Fiero_Freak:

I have same kind of jumping that you have. I had it before changing (very loose) timing chain and have that with new timing chain.

It makes things weird but when A-B shortcut is removed timing jumps to ~25 degrees and it will not jump anymore. If ECM controls timing and there is no broblem then, I think pickup coil and magnet should be fine. That would lead to ignition module and it's own ignition timing circuit. I'm pretty sure it makes timing jump.

Normally ECM controls timing so it is not a broblem with normal operation. Just make sure avarage timing is about right.

Mine does it in both conditions. w/ and w/o the ALDL jumpered. I have a cable.....where is a good free software that I could get to see a little more of what's going on?

This is what I use :

http://winaldl.joby.se/

there are more at the bottom of :

http://www.aldlcable.com/

I did think of one other item. I don't have a timing chain guide in mine. Does anybody else. Thinking it might create the problem.

------------------
85 GT 3.4
Auto 3.08
14.9 @ 90 1.9 60"

There's really not one on these types of engines...I would think the timing cover is the best your going to get.

The piece I'm talking about goes between the two gears and inside the chain. Has two bolts holding it in. Can be seen in chevy power book #24502488 page 174. Hope I'm not getting off the subject.

------------------
85 GT 3.4
Auto 3.08
14.9 @ 90 1.9 60"

Hmmm I'm trying to remember it's been so long since I changed it...I'm just getting back to putzing with the car now. If I get that far I'll post it, but I'm sure someone else knows off the top of their head.

That piece's primary purpose is to dampen resonant standing waves in the timing chain for the purposes of extending its wear life. The chain is tight enough under normal circumstances to prevent significant timing changes from slack.

JazzMan

you could be geting cam walk where the cam moves a bit forward and backward in the engine making the timing to change the way to fix it is to put a cam button on the front of the cam but cam walk is on roller cams but some times on a flat tappet cam

The timing jump is WAY to fast for that.... At least it seems that way to me. If there was that much banging around in the engine, I would think you could definately hear it. Just sounds like something ignition related, not mechnical.

The ECM has no control on timing when it's in bypass mode (jumping the pins in the ALDL connector), instead the module relies on it's own built-in rudimentary timing curve.

Do you have a scope? You can use that to see if the pickup coil is false-triggering the module. Also, have you considered that your timing light may be bad?

JazzMan

quote Originally posted by JazzMan: Also, have you considered that your timing light may be bad? JazzMan

Now that's a great idea, there's nothing worse than bad test equipment, it will make you insane. (or moreso if already a Fiero owner)

Timing light it good as I've used it on a couple other cars....

Well I swapped the computer tonight, not really a change. Didn't have a chance to put the light on it...but once it warms up...it wants to die a little more....or if you rev it and it comes back down it wants to die. Do you guys this maybe IAC valve? If you're driving it(went for a short drive, and stop it almost dies or does die. Doesn't seem like the lock up on the coverter at all, just like the timing if fumbling around and then idle rises really fast and then it's find. Sometimes wants to die when to tap immediately on the throttle then picks up. Just seems to be a bit off.

Sounds like you have done everything. The next thing I would do is swap out the distributor and cap and rotor.
Don

quote Originally posted by Fiero_Freak: Timing light it good as I've used it on a couple other cars.... Well I swapped the computer tonight, not really a change. Didn't have a chance to put the light on it...but once it warms up...it wants to die a little more....or if you rev it and it comes back down it wants to die. Do you guys this maybe IAC valve? If you're driving it(went for a short drive, and stop it almost dies or does die. Doesn't seem like the lock up on the coverter at all, just like the timing if fumbling around and then idle rises really fast and then it's find. Sometimes wants to die when to tap immediately on the throttle then picks up. Just seems to be a bit off.

You could try a new iac & clean out the passage, it won`t hurt at this point , did you test the tps ? Or replace the cts to ecm & check all connectors and wires they do go bad over the years... Double check you vac lines, also pcv vavle , I know sounds weird , but it bumped me around for a while.

one other thought
I have notice my timeing jumps around a little with one of the following
cold engine
old plug wires and or old spark plugs
and "just because"

Im sure you have covered these off on your check list but i thought id toss them out there

Leaning toward screwed up injectors or even a cold start injector. What's a good way to tell if one is stuck open? Smells rich like it's bogging down.

been thinking on this a bit. if you jumpered the aldl connector, the ecm is basically out of the picture, it is soley run by the module. rpm does not seem to vary the timing much in this mode, but it can move it slighly. what are your rpms when timing it? do they stay fairly steady? with the jumper on, it should sit at 1k, but seems it can vary 200 rpm or so and not move the mark more than a degree at most. so if your rpms are steady, the mark should not move.
frpm your list of what was replaced, dist/wires/plugs/etc you really only have 2 things left:
Mechanical with the cam/gear
or wiring.
There was a way, IF I can find it to unplug one of the ignition module plugs and dummy up the control line so you could start it without the ecm and wiring , but don't wait on me finding it, it was like 8 years ago I found it.

for mechanical, I would take the cap off, and mark the rotor position. rotate the crank until the rotor just moves , then rotate the crank back and try to note how much you have to move the crank to move the rotor to the starting position. then rotate till it moves again. there should be almost no foward reverse play, if there is, it could very well be mechanical.

quote Originally posted by Fiero_Freak: Leaning toward screwed up injectors or even a cold start injector. What's a good way to tell if one is stuck open? Smells rich like it's bogging down.

I`m taking it you have a service manual, and a fuel gauge, what you want to do is the leak down test --by pinching off your** pressure line **, if the pressure does not hold , you want to check injectors & cold start injector.

Yeah... Looks like I'm going to have to pull out the big book, but it's going to have to wait until next weekend. I've got to work today to get some things done. At least I've got somewhere to try next... BTW if the tach is ANYWHERE close, the idle is very high. First thing next week I was going to pull the upper intake and test all the vacuum lines and clean the TB, then reset the IAC... Maybe I'll do the fuel pressure test first so I can get to the injectors while I'm there.

Thanks guys.

quote Originally posted by Lilchief: I did think of one other item. I don't have a timing chain guide in mine. Does anybody else. Thinking it might create the problem.

I dug up a pic I took when I did the timing chain set on my wife's 86GT, it shows the timing chain guide.

quote Originally posted by Fiero_Freak: Yeah... Looks like I'm going to have to pull out the big book, but it's going to have to wait until next weekend. I've got to work today to get some things done. At least I've got somewhere to try next... BTW if the tach is ANYWHERE close, the idle is very high. First thing next week I was going to pull the upper intake and test all the vacuum lines and clean the TB, then reset the IAC... Maybe I'll do the fuel pressure test first so I can get to the injectors while I'm there. Thanks guys.

May be a good time to replace those old plastic lines with www.rodneydickman.com aluminum lines. On the high idle check egr tube for cracks also the tube that runs out the rear of T.B. to the intake, Those 2 are very common vac leaks and create quite a high idles as well.

OK... just to touch back on the subject... I've found several issues an wanted to let you know where I'm at now. I found one melted through line(although it looked like it sealed itself off) that melted NEXT TOO the EGR tube. It's the line that runs to the EGR solenoid.
Why was the tube that hot... well the EGR failed slightly open!
This would probably account for why the cat is FRIED! There was nothing but a little brick in there. I'm going to replace that and the 02 sensor today to be on the safe side.
I think at least one of my injectors was stuck open, or maybe the cold start injector was leaking. We cleaned the fuel system with the 3M kit. The clicking of the injectors seams to be much more pronouced now, along with the extremely rich smell.


After doing all of this I still have a high idle, 2100 tach (1000 ECM), but I was able to get the timing set much better. Only a 2deg swing now but I've found that my tach is way off. Reads way to high. I've pulled my MSD 6al, but it's still high compared to the ECM. I'm going to post another topic to try to run this one down. I've done a little searching and found a few things, but I'd like to see if anyone else knows much about it.

Thanks guys.

------------------
Dana Mitchell
Member of the Gateway Fiero Club
86 SE Red w/ Black 3.2L w/ T-440, 87 GT Maroon w/ Silver Auto, 87 GT Blue w/ 5-Speed
95 Impala SS, 95 Roadmaster Estate Wagon w/ Air Ride
06 Colorado 3.5L, 06 HHR (wife's ride), 91 CBR1000F

[This message has been edited by Fiero_Freak (edited 05-29-2006).]