My car is an 86 notchback 4 speed V6

this is the third time this has happened. First time, I was driving back from a car show out of town and check eng light came on. Went to downshift and gave it some gas coming back into town, and I got no response. then BANG - it backfired and sounded like I was being shot at. I rolled into a parking lot before it stalled out. my thermostat cap was only half on thanks to my buddy who was helping me top up the coolant the other day - so I filled my car up with some coolant and tightened it all the way thinking that would fix the problem. if it makes a difference, thats when I found out I didnt have a thermostat either! I went and got one the next day and put it in.

second time, my friend and I are driving to a party, im going under an overpass at about 50 KM/H (30 MPH), and again it backfired and wanted to stall out. So I pulled over and let it sit for a couple minutes... then I was on my way again with no problems

Now, today, I was driving home on the highway at speeds from 100 - 150 KM/H (60 - 90 MPH) and my check engine light came on. I made it most of the way home, but when I proceeded to slow down and turn onto an off ramp - I had no throttle response again. I pulled over and let her "idle" (very rough) for a couple minutes and shut her off. started her up and made it the rest of the way home with no problems.


other things to note: my car starts up right away when its cold/been sitting over night but has a very hard time starting up after its just been driven or the engine is still fairly warm
I have terrible gas mileage ... in the 80 KM (50 miles) that I traveled just today I went through nearly a QUARTER TANK on 87 octane. Now I know these cars are no economical savior but COME ON!

I need to fix this ASAP

thanks

Welcome to the Forum. If you downloaded the code(s) it might help diagnose what's going on. If you're not sure how, then ask and I or someone else will explain. In the meantime, I did a quick search of the Service Manual to see what it says are the most likely causes of backfiring. Most tests need test equipment, but for waht it's worth, page 6E3-B-6 says the following:

Check:
Compression - look for sticking or leaking valves
EGR operation for being open all the time
Valve timing
Output voltage of ignition coil using a shop cscilliscope or spark tester
Spark plugs for crossfire (also inspect distributor cap, sprak plug wires, and proper routing of wires)
Ignition system for intermittent conditions
Ignition timing

Yep, run the computer codes to narrow your search.

in my haynes book under trouble shooting is this so check these out.


#4 engine hard to start while hot
1. Air filter clogged
2. Fuel not reaching the fuel injection system
3. Corroded battery connections especially ground.
#15 engine back fires
1. Emission system not functioning right
2. Ignition timing incorrect
3. Faulty seconardy ignition system (cracked plug isulaters,faulty plug wires,distributor cap and rotor)
4. Fuel injection system in need of adjustment or worn excessively
5. Vacuum leak at fuel injectors , intake manifold,vacuum hoses,
6. Valves sticking.

thanks for the replies - I ran a code scan and nothing came up. No DTC's or anything. When I got the car recently I replaced the rotor, distributor, spark plug wires and spark plugs. The car came with a MSD coilpack if that makes a difference. sounds like a problem with my fuel delivery or timing?

[This message has been edited by Flux (edited 10-08-2012).]

quote Originally posted by Flux: thanks for the replies - I ran a code scan and nothing came up. No DTC's or anything. When I got the car recently I replaced the rotor, distributor, spark plug wires and spark plugs. The car came with a MSD coilpack if that makes a difference. sounds like a problem with my fuel delivery or timing?

i am think fuel delivery more then timeing but don't rule out timing cuse it could be it i would do it as a last resort. have you ever replaced the fuel filter? the tanks rust, fuel can be bad, and filter plug. this is why they say to replace them every 30,000 miles not like newer car with 100,000 mile tune ups got to rember this is a 198o's car not a 2012. scored injectors is the big posibilty hook a fuel pressure gague up and prime it. see if it holds fuel and if so how long could be leaking injectors.

[This message has been edited by blacknotchback86 (edited 10-08-2012).]

just replaced the fuel filter tonight, maybe its a mental thing but it seems to be running a bit smoother. I'll do a compression check & vacuum leak test to see if there's any issues there; i'm sure there's a vacuum leak somewhere

do you have access to something that can look at the datastream? i.e. winaldl, tunerpro, snapon scanner?

as in a laptop? i'm not familiar with those programs / datastreams. I assume those are live diagnostic tools that will tell me what the ECM is doing?

My money is on your ignition module being the problem. The symptom of applying throttle and hardly getting any response coupled with backfiring suggests ignition system trouble. If the module malfunctions while you're driving and severely retards timing and suddenly reapplys it you may have a large quantity of fuel being ignited in the exhaust system resulting in the backfire you're hearing.

Letting it cool off and having no trouble afterwards also suggests that may be the problem.

this little bugger?

bump

quote Originally posted by Flux: this little bugger?

No. That is the ignition coil. The Ignition module (ICM) is that black box under the distributor cap.

quote Originally posted by Flux: just replaced the fuel filter tonight, maybe its a mental thing but it seems to be running a bit smoother. I'll do a compression check & vacuum leak test to see if there's any issues there; i'm sure there's a vacuum leak somewhere

also check to see if the cats are pluged with the vaccum gague when testing for vaccum leaks. could be but i do not think it is so that is if doing it this way.

Ignition Module sounds likely due to its running fine at times. (Its a matter of time though) Could also be Clogged fuel filter, or any number of things What have you done to narrow down results?

quote Originally posted by Flux: I have terrible gas mileage ... in the 80 KM (50 miles) that I traveled just today I went through nearly a QUARTER TANK on 87 octane. Now I know these cars are no economical savior but COME ON!

That's actually about right. If you get 340 KMs out of a tank of gas you're doing REALLY good.

quote Originally posted by Phirewire: Ignition Module sounds likely due to its running fine at times. (Its a matter of time though) Could also be Clogged fuel filter, or any number of things What have you done to narrow down results?

I replaced the fuel filter, and the problem still persists. I scanned the ECM for codes with an OBD1 scanner and nothing came up. Rotor, Dist cap, taylor 8MM wires and iridium NGK plugs all replaced a month ago. I had a buddy with a timing light help me adjust the timing to how the directions say to do it (use an average of cyl 1 and 6 timing I think) Put a new stant 190 thermostat in recently because I didn't have one at all! uhm.. thats about it really

it's gotta be something electrical - the check engine light only comes on after cruising at speeds above 100 KM/H and that's when I start having the issue...

also - i'm pretty certain the leak I have is coming from the distributor O-ring - i'll be doing that job in a week or so. I might as well replace the ICM as well since i'll have the distributor ripped out.

bump - did the paperclip engine light scan and got code 33 and 34

Those are MAP sensor codes. Check the vacuum hoses around the MAP sensor.

Unplug that electrical connector on the MAP.....and go for a drive. If it drives better, the MAP should be replaced.

[This message has been edited by Gall757 (edited 10-30-2012).]

I pulled my ignition module out a long time ago and mounted it to one of the frame rails on a large (and I do mean large) heatsink with a fan on it.
Runs cool as a cucumber now. The fan runs with the fuel pump.

It might be that the white heat transfer goop that they put on the modules dries up over time and the temp goes up, make sure you put some fresh on the replacement module
(it does sound like that is your problem BTW)

car stalled out on the highway again... except the radio was flickering on the way and the battery didn't have enough juice to start her back up. Boosted it and made it to a buddies house and had to tow it home today. pretty sure the alternators toast. I'm at the end of my f*cking rope with this car.

Could have swore i posted on this saying it was alternator, maybe it was another one. If you Step on the gas and it catchs it it jumps the battery a bit correct? and it acts fine for a bit. Alts prob done.

nope, it killed the battery too.

When mine was going (300$ bill to replace) it would run and start to die if I got to it soon enough and floored it, the car jump charged to about 15v and it was fine till it got really bad. Its the Regulator thats bad inside the alt, which can't be replaced by itself since its inside on the fiero.

haven't had the issue for a while, but I went on a cruise today with a buddy and did some spirited driving, nothing extreme. on the highway I had it wide open and as I shifted at 5 grand, the car stuttered and died when I put in the clutch. I had to keep restarting my car and limping a few feet forwards all the way home (luckily I wasn't too far). It even gave me a nice gunshot backfire again! lol. anyways, here's a video of me trying to get home on my street... ignore the beeping noise, thats my ipod turning off/on.

starts backfiring at about 0:45 seconds in.


http://www.youtube.com/watch?v=piIMZ_zQLFo


maybe someone can ACTUALLY help me now that I can show how its acting. I still have to live with the 2.8 for a couple more months until I get all my swap parts in order.

PS: no, its not the alternator.

[This message has been edited by Flux (edited 02-05-2013).]

car died today and now it won't start at all....... fuel pump primes like normal......... what could it be? ignition control module maybe ?

[This message has been edited by Flux (edited 02-12-2013).]

quote Originally posted by Flux: car died today and now it won't start at all....... fuel pump primes like normal......... what could it be? ignition control module maybe ?

i saw somewere if the contol module goes bad the tach wont rise while cranking. supposed to crank to 100-200 rpm. try that and see what happens. hope you find the issue quickly

yea i read that and the tach didn't move when I checked it out, so I went and bought an ICM at a local parts store. it starts up and drives normally. hopefully that was the issue. thanks