I was driving my 86 SE V6 the other day, and it was running perfectly, no SES light. Then, the car started being sluggish and then had no power. I barely got it home, slowing down to 40 MPH on the steep hill on SR32 in Batavia, Ohio. The exhaust note (sound) has changed, and now the car gurgles on deceleration. When I got home, the first thing I checked was fuel pressure, since it was acting like bad fuel pump. The pressure was 45PSI with engine off, 39-40 PSI idling, and 48 PSI WOT. So I know it has fuel pressure. Replaced MAP Sensor, tested TPS, both test good. Next, I proceeded to check the timing, to which I had set to 10 deg BTDC previously. NOW, the timing mark is off the low-end of the scale, estimation at about 2 Deg after TDC. So my timing has jumped 12 degrees retarded. I know it is not the harmonic balancer outer ring moving with respect to the crank, because that would not cause the no-power scenario. I adjusted the timing to 10 Degrees BTDC. The car has power again, but falls on its face at stop signs(sometimes stalls) and has no power and is sluggish until about 3K RPM. above 3K it pulls fine. I noticed the A/C pulls the motor down like crazy now. Before, the A/C barely had an effect on the motor when engaged. Also car has no CAT.

Summary:
No power, checked fuel pressure which was fine.
Checked timing, jumped 12 degrees retarded. Reset timing to 10Deg BTDC
Now stumbles, stalls on take-off
No power until 3K, above that it pulls fine.

I am thinking I slipped timing chain. that is the only explanation i can think of.

Help would be greatly appreciated.

Thanks
Matt Howard

[This message has been edited by mattman134 (edited 07-23-2010).]

How much slop have you in the distributor rotor? You may have to pull the timing chain cover to see for sure if you jumped a tooth or two.
Loss of power doesn't sound like your harmonic ballancer slipped but it's relatively easy to index that out just to rule it out.
Let me ask if you pulled the codes yet or tried to reset the ECM?

[This message has been edited by jetman (edited 07-23-2010).]

There was no codes set in the ECM. Also I pulled the small single-pin connector by the battery to reset the ECM. Still no difference.

Any possibility it's a clogged cat?

quote Originally posted by carnut122: Any possibility it's a clogged cat?

NO CAT

How many miles on the engine (specifically, on the timing chain)? If we're talking 6 figures, then the chance of the timing chain stretching and jumping teeth is pretty good.

The engine is not the original motor. The car itself just turned 190,000 miles, but the engine is of an unknown mileage. The engine is from an 87 GT and has a very small amount of the infamous rod bearing rattle at about 2000 RPM, so it is probably in the 6 figures. I just dont want to have to pull off the belts, water pump, alternator.......timing cover to see IF it could be the timing chain. But I am slowly weeding things out to the point that it is leaning more and more towards timing chain. Luckily, I have a brand new cloyes timing set in a box.
Thanks

can you get to it from the oil pan or is that the updated design?
should be able to feel the slack from down there.
also good time to check you lower end bearings if you take off the pan

Ok first thing, try swapping the MAP sensor out with a known good used one, go rob one from another GM car for testing purposes then put it back if it fixes your problem, I don't think it will, but its Worth a shot before you start on what I think your problem actually is.

Try ramping the timing up to about 18 degree's if it runs better, I'd bet money your timing change has slipped a tooth.

My mother called me and this was the story.

She was driving her 86 SE V6 4spd home and it was a bit harder to start when she left work, and then about 1/2 way home it lost almost all power, in order to make it up the hill from the Port Mann bridge she had to have it to the floor. When it got home it would not re-start, I started with new module, then new distributor with new pickup coil, then new primary coil, checked the plugs and still would not start grabbed my timing gun and proceeded to work on that.. I cranked the min idle set screw wide open and with a jumper box hooked to the battery cranked it with my foot to the floor and eventually got it to run enough to check the timing I think I had to run it up to almost 24 degree's initial advance to get it to run enough to get it to my garage. I got the water pump off, timing cover off and sure as $hit, there was a full 2 inch's of slop in the chain. A new timing set is cheap for the Fiero, just time consuming to change. I did take a shortcut and re-used the crank gear, but that was over 300 daily commutes later and car is still fine. (1.5 years of driving in bumper to bumper city traffic and when she gets an open spot she will drop the hammer drop 2 gears to pass as many people as possible) Even at 50 years old, she still loves to drag race with me from stop lights.

Clip from my old archived thread see link for video of a sloppy chain below.

I am posting this mainly to show that is is possible. I still can barley believe it. But I guess any new knowledge is good knowledge.

Ok so the short version of the story.

I have never in the history of driving Fiero's ever heard of a 2.8 timing chain actually fail or get loose enough to jump a tooth. 99% of the time a 2.8's main or rod bearings or valves or rings fail long before a chain can go bad. But there is a first for everything. If you want the back story with pics, you can see this link. (pics include a totally bent timing cover bolt that had snapped off, and relationship of crank gear to cam gear)

http://www.westcoastfieros....sts.asp?TID=508&PN=1


Looks like it is a simple shot chain. Just watch the video. Ignore my old codger of a voice. I can�t believe I did not notice this earlier. I must have had the crank backed up just enough that the slop did not show. When I started turning the crank so it got tight on one side the slop really showed up on the other side.

I did manage to get the bent stud out as well. I was lucky enough to grab it with a pair of vice grips and twisted it out without it snapping off in the block. Took me the better part of an hour inching it out, but it came out and even had clean threads.


http://www.members.shaw.ca/...timingchainloose.wmv

See Video Above.

This was not from any of my personal Fiero's, this one belongs to my mother. Yes my whole family drives Fieros.

------------------
85GT Soon to be 87GT,93 Eldorado 4.9, 5spd Dual O2 Custom Chip, Custom Exhaust. MSD Everything Capt Fiero --- My Over View Cadero Pics Yellow 88GT 5spd Full Poly Suspension, Lowered 1/2" in front, Corner Carver.

Before you readjusted the timing...
Was the distributor in the same position that you left it?
If the bolt had gotten loose and allowed it to turn, it's natural inclination would have been to retard itself.

Having said that...
The cam gear has 40 teeth. 360/40 = 9 degrees per tooth.
It's possible that it jumped. I wouldn't have pictured that happening, however.
But I suppose it's possible.

Distributor was in same position as I set it 6 months ago. The bolt was tight.

Matt

Did you check the fuel injector fuses? There is one for each bank and if one blows your engine will run much as you've described.

quote Originally posted by mattman134: Distributor was in same position as I set it 6 months ago. The bolt was tight. Matt

Okay. Based upon that, and Capt Fiero's experience, I have to think that you are on the right track with the jumped chain. Not much else it could be other than the ECM losing its mind. (The ECM thing is pure last-ditch speculation, with no basis in reality other than it would be a lot easier to replace. )
Sounds like lots of fun (not) but at least you can do it in the car.

I did swap in a spare ECM- no difference.
to johninconifer: I had a problem about 2 years ago which turned out to be the TBI INJ1 fuse was old and fatigued and the fuse filament came loose INSIDE the fuse. I also checked the injector banks and they both have good clean power.

Matt

I lost my chain at 180K. If you want to properly diagnose a skipped chain, you need a dial indicator, and a piston stop. And then you need to find Proper TDC (or at least confirm that the harmonic balancer is correct. and then measure the center point of the overlap between Intake and exhaust lobes between the exhaust and intake stroke.Typically its at top dead center or within a couple degrees. Since there are 20 teeth on the crank sprocket, One tooth is 18 degrees, and it will always skip in the retarded direction. It'll be stupid obvious if the chain skipped because they skip so far with just one tooth.

Seems to be at least fairly consistent with your symptoms though, but 12 degrees retarded on the dizzy is a bit on the low side for a chain skip.

quote Originally posted by Fierobsessed: I lost my chain at 180K. If you want to properly diagnose a skipped chain, you need a dial indicator, and a piston stop. And then you need to find Proper TDC (or at least confirm that the harmonic balancer is correct. and then measure the center point of the overlap between Intake and exhaust lobes between the exhaust and intake stroke.Typically its at top dead center or within a couple degrees. Since there are 20 teeth on the crank sprocket, One tooth is 18 degrees, and it will always skip in the retarded direction. It'll be stupid obvious if the chain skipped because they skip so far with just one tooth. Seems to be at least fairly consistent with your symptoms though, but 12 degrees retarded on the dizzy is a bit on the low side for a chain skip.

10-12 degrees retarded from 8 degrees advanced is about the angular displacement you're describing.

quote Originally posted by Fierobsessed: Seems to be at least fairly consistent with your symptoms though, but 12 degrees retarded on the dizzy is a bit on the low side for a chain skip.

Unless it jumped on the cam gear. Each tooth is only 9 degrees.

[This message has been edited by Raydar (edited 07-24-2010).]

quote Originally posted by Raydar: Unless it jumped on the cam gear. Each tooth is only 9 degrees.

C'mon Raydar! You know better then that!
Yes, if the cam skips a tooth, THE CAM rotates 9 degrees, but... if you rotate the crankshaft back so that the cam is where it was, it has to rotate 18 degrees, and all cam and ignition timing is done off the crankshaft only, so if the chain skips a tooth on either the crank or the cam gear, the end result is a 18 degree net change in crankshaft degrees in either case.

I disagree.
We're talking about cam (and distributor) timing.
The cam gear has 2x as many teeth as the crank gear. It takes two revs of the crank to make one rev of the cam. (Remember the compression stroke...)
If the chain just jumps one tooth on the cam gear, it will be half as much timing error as it would if it jumped on the crank gear.
Remember, this is all referenced to the timing mark on the damper. That's what the timing light is looking for.

Anyone want to referree?

Edit -- WAIT!!
I've got it backwards. Jumping a tooth on the crank will cause half as much discrepancy as jumping a tooth on the cam.
They will not be the same.

[This message has been edited by Raydar (edited 07-25-2010).]

quote Originally posted by mattman134: NO CAT

We can take that one off of the list!

sounds like a chain issue to me too. If it didnt jump a tooth, maybe its just stretched far enough to throw it off that much.

quote Originally posted by mattman134: I was driving my 86 SE V6 the other day, and it was running perfectly, no SES light. Then, the car started being sluggish and then had no power. I barely got it home, slowing down to 40 MPH on the steep hill on SR32 in Batavia, Ohio. The exhaust note (sound) has changed, and now the car gurgles on deceleration. When I got home, the first thing I checked was fuel pressure, since it was acting like bad fuel pump. The pressure was 45PSI with engine off, 39-40 PSI idling, and 48 PSI WOT. So I know it has fuel pressure. Replaced MAP Sensor, tested TPS, both test good. Next, I proceeded to check the timing, to which I had set to 10 deg BTDC previously. NOW, the timing mark is off the low-end of the scale, estimation at about 2 Deg after TDC. So my timing has jumped 12 degrees retarded. I know it is not the harmonic balancer outer ring moving with respect to the crank, because that would not cause the no-power scenario. I adjusted the timing to 10 Degrees BTDC. The car has power again, but falls on its face at stop signs(sometimes stalls) and has no power and is sluggish until about 3K RPM. above 3K it pulls fine. I noticed the A/C pulls the motor down like crazy now. Before, the A/C barely had an effect on the motor when engaged. Also car has no CAT. Summary: No power, checked fuel pressure which was fine. Checked timing, jumped 12 degrees retarded. Reset timing to 10Deg BTDC Now stumbles, stalls on take-off No power until 3K, above that it pulls fine. I am thinking I slipped timing chain. that is the only explanation i can think of. Help would be greatly appreciated. Thanks Matt Howard

Describes every problem my car had until I replaced the timing chain... mine was like this when I got it and the timing had been reset. When the chain was replaced and the engine buttoned up, I found the base timing to be almost 20* BTDC, it had been set with the old chain previously at 10*. The chain must have jumped a tooth and was severely stretched, probably after it tried to kill the chain guide... which it had murdered thoroughly. See my thread below for my results...

Sweet mother of rattle...

[This message has been edited by carbon (edited 07-26-2010).]

I definitely had a timing chain jump on a 2.8 a few years back. I was cruising down the freeway and came upon some traffic right as I got near my exit, and as I decelerated the engine coughed and choked. I staggered through the exit and had to limp home, keeping the revs up to keep the engine running. When I got home the engine would not start again; it would fire as I cranked it, but would not stay running on its own. I didn't know what was wrong, never expected the timing chain to jump. I finally got the engine to run -badly- by twisting the distributor until the timing was at some unbelievable value. I'm guessing that it jumped some more while I was trying to start it. Sounds worse than what you describe.
Anyway, I could tell there was hella slack when I took a big long wrench to the nut on the crank pulley and rocked it. As I rocked it I watched the distributor rotor and there was a definite delay between the relative motions. Same when I looked at the valvetrain through the oil fill hole in the valve cover. I think I pulled the spark plugs too, so I wasn't working against engine compression- I ain't that strong.
Long story short- the timing chain had stretched. I replaced the timing chain (and the water pump too; it has to come off anyway) and the engine ran great after that.
If this ends up being your problem too, I have a few tips from experience that might help you.

I appreciate all the input and advice. Turns out to be timing chain. Looks like I am going to be getting dirty.....

Matt Howard