Hunting Gremlins and Misfires in my 86 Fiero GT (Page 2/2)
Cliff Pennock JUN 15, 03:58 PM
TL;DR 😉

Did you replace the ignition module? That would have been the first thing I'd replace when it misfires.
fierofool JUN 15, 06:35 PM
I found the problem with my misfire. It was caused by the leaves and debris collected around the front bank of plugs. Took an air blow gun with a long extended tip and blew all the debris out and the problem went away. Two tanks of fuel through it and not a single misfire.
Notorio JUN 16, 11:39 PM

quote
Originally posted by fierofool:

I found the problem with my misfire. It was caused by the leaves and debris collected around the front bank of plugs. Took an air blow gun with a long extended tip and blew all the debris out and the problem went away. Two tanks of fuel through it and not a single misfire.



So that means the debris was causing the plugs to short to ground?
Patrick JUN 17, 12:30 AM

quote
Originally posted by bootdsc:

Any good reason to not use wheel spacers with the Fiero? I really like the stock wheels and I don't want to replace them just to get the offset I need



There are some members here who think using wheel spacers/adapters rates right up there with cutting a coil off a spring... they don't feel it's right. IMO, it depends to what degree in both situations it's being done.

I've run these 1" hubcentric spacers on the back (just the back) of my Fiero(s) for the last 14 years with absolutely no issues They bring my Sunfire wheels (with the wrong offset) out to the edge of the fenders (instead of being tucked in too far).




Keep in mind that using spacers to push wheels out beyond where the factory intended the wheels to sit will put greater stress on the wheel bearings.

[This message has been edited by Patrick (edited 06-17-2020).]

Gall757 JUN 17, 08:55 AM

quote
Originally posted by Notorio:


So that means the debris was causing the plugs to short to ground?



Yes...with a little moisture added.
fierofool JUN 17, 09:56 AM

quote
Originally posted by Gall757:


Yes...with a little moisture added.



The plug boots also needed a reapplication of dielectric grease. I apply a liberal bead around the opening of the boot so it's distributed along the plug ceramic as the boot is installed. Also helps prevent the boot from sticking to the plug.

bootdsc JUN 18, 05:11 PM
Thanks for the suggestions. Since last time here's what I've done.

Reinstalled the spark plugs and cleaned a bit of oil and gunk from around the area but there wasn't much. My Fiero was kept in a garage. Plug boots got a good sized bead of dialectric.

Cleaned the ground that's below the ECM, it was slightly corroded.
Should there be more than 1 wire at that ground point?

Cleaned the positive distribution block by the battery. Everything was very corroded.

Checked for ECM ground on the engine block, it's still there and intact connected by two bolts but I haven't removed them to clean it up. idk how to get back there.

Replaced the fuel pump and strainer. Tank looked perfectly clean but idk what might be under the plastic insert. I saw no signs of rust or gunk.

I have 3 ICM's, 2 are new 1 is old and there's no change when swapping between them.

Installed a new MAP sensor.

Replaced all remaining vacuum lines and boots that leaked.

Reset the throttle body idle set screw. The previous owner drilled out the the plug and fcked with it.

My current thought is I'm intermittently losing vacuum which stops the fuel pressure regulator from working so when I try to accelerate the injectors are starved.

For the last few days I've had to use starting fluid to start her up if it's sat more than like 4 hours between restarting.

This morning I drove around the block (idle speed mostly) until I got a check engine light, it was code 35 and 44. The incorrect idle isn't important now but running lean sure is, this is what I've been fighting with for 2 weeks.

Tonights project will be installing a new fuel pressure regulator and replace the vacuum line boot. Maybe replace the water temp sensor, the thermostat and do a cold start injector delete since I live in the hottest part of the USA.

Engine shot just cause and yes I know the IAC is disconnected in the pic. https://imgur.com/a/AHRBvMI

[This message has been edited by bootdsc (edited 06-19-2020).]

bootdsc JUN 18, 05:15 PM

quote
Originally posted by Patrick:

I've run these 1" hubcentric spacers on the back (just the back) of my Fiero(s) for the last 14 years with absolutely no issues They bring my Sunfire wheels (with the wrong offset) out to the edge of the fenders (instead of being tucked in too far).




Keep in mind that using spacers to push wheels out beyond where the factory intended the wheels to sit will put greater stress on the wheel bearings.




I hadn't thought about added stress on the bearings but I did figure I'd need to adjust the camber. I just like the stock wheels so much I can't part with them just for a wider stance. 1" out front and back and I wouldn't even need to add fender flares, do you have a source for the spacers you used?
Patrick JUN 18, 05:38 PM

quote
Originally posted by bootdsc:

do you have a source for the spacers you used?



eBay, where else?

Just make sure the spacers are indeed hubcentric.
bootdsc JUN 21, 01:49 AM
For anyone who finds this thread ill summarize, there were multiple problems which made it difficult to find the one causing the intermittent lean condition which in tern caused misfires.

Ended up being a pulsator with a non visible crack that prevented the fuel from reaching any higher than 12psi when it should of been 36-45psi. Solution is to replace the pulsator with fuel submersion rated 5/16th hose and use two fuel line hose clamps to hold it in place.