85 gt v6 2.8l -- My car runs amazing when I first start it up and start driving but when the car warms up it starts to random misfire, and I get low acceleration and power under load . I've replaced some stuff so far
I think thats everything I can think of off the top of my head, I also took apart egr and cleaned it out and gave it a good scrubbing. Any help would be appreciated I love this car and just want her to run well.
Gonna try cleaning and testing IAC tomorrow as that seems to be a common issue from all of the readings I've done on the forums here.
[This message has been edited by Monkeybean007 (edited 03-23-2020).]
The ceramic material inside the cat convertor tends to crumble with age and sometimes will almost completely block the exhaust flow. It is pretty random, sometimes the chunks will settle out and you dont notice it as much. Usually a good full throttle rip through first and second gears will have the engine choaked pretty well.
The ICM sometimes gets corroded and needs to be cleaned and a new layer of heat transfer paste put on. That would be consistent with it running rough after it warms up.
------------------ 86 GT built 2.2 ecotec turbo rear SLA suspension QA1 coilovers on tube arms
[This message has been edited by wftb (edited 03-23-2020).]
Engines running cold use default computer values, while a hot engine uses sensor inputs. IF one of the sensors is bad, it will only bother the engine when it is hot. The coolant temperature sensor, (CTS), is a candidate. ICMs will do this also because they expand when they get hot, and sometimes break solder joints on the internal board.
[This message has been edited by Gall757 (edited 03-23-2020).]
I've already replaced coolant sensor and no codes are being thrown unfortunately, replacing/removing cat is also on my list of things to do, I was thinking sensors as well, so icm seems to be the next thing I should check out?
What new plugs and plug wires? New either could still have problems and more so w/ "gimmick" or "Performance" ignition parts
discon the tach filter and See my Cave, HE Ignition
------------------ Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should. (Jurassic Park)
85 gt v6 2.8l -- My car runs amazing when I first start it up and start driving but when the car warms up it starts to random misfire, and I get low acceleration and power under load.
Not sure why you'd think the Idle Air Control valve would have any effect on a random misfire and beyond half-throttle issue.
I agree with what Gall posted. Get a scanner (or WinALDL) on there to see what's going on with the sensors.
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Originally posted by Gall757:
Engines running cold use default computer values, while a hot engine uses sensor inputs. IF one of the sensors is bad, it will only bother the engine when it is hot.
Because it had a super rough idle, tested the IAC valve and no resistance or anything pulled it out and the mechanism was stuck open wouldnt adjust, hence the replacement.\ And I'm going tyhrough parts that change when the engine heats up, the IAC is one of those. I also don't know where to get a scanner other than the one I have seen on the fiero store, and the car dosen't have a check engine light up, I know I'll still be able to check stuff without it but just thought that might be an important piece of info, Is there a scanner I can get off of amazon ?
[This message has been edited by Monkeybean007 (edited 03-23-2020).]
whats the cable called for my fiero its not an obd1 as I tired that at the local parts store and it didnt fit, the oine they used was an alldata one but when I look those are super expensive kits lol.
Buy a sawzall and cut the cat out and put a straight pipe in for now. You can buy exhaust pipe and adapter pieces at any prts store. Your cat is a year older than mine and mine was plugged 14 years ago. Get a new high flow cat if it isnt plugged. They are not much money and better than the original.
------------------ 86 GT built 2.2 ecotec turbo rear SLA suspension QA1 coilovers on tube arms
Buy a sawzall and cut the cat out and put a straight pipe in for now. You can buy exhaust pipe and adapter pieces at any prts store. Your cat is a year older than mine and mine was plugged 14 years ago. Get a new high flow cat if it isnt plugged. They are not much money and better than the original.
Thanks I'll definitely give that a try and I'll pick up a cable as that seems like the easiest solution because from what I'm hearing it'll essentially tell me what's wrong even though it's not throwing codes correct?
That I don't know but if other people that have that equipment say it will work I would believe them. I just think you should do one thing at a time and not waste a bunch of money buying stuff you dont need. That being said, working diagnostic tools always come in handy sooner or later.
------------------ 86 GT built 2.2 ecotec turbo rear SLA suspension QA1 coilovers on tube arms
That's what I've been doing just one thing at a time and seeing if it fixes the issue, if it doesn't the part needed to be replaced anyways as most sensors are old, just trying to narrow it down so I can have it running well while I replace everything else 😂
The piece of plastic in the distributor where the two different cables plug in is the ICM. While you have the cap off look at the pick up coil. If it is falling apart it needs to be replaced. It requires the removal of the distributor to get it out. When removing the distributor always replace the O-ring or you will have an oil leak.
This is what a good pick up coil looks like.
[This message has been edited by phonedawgz (edited 03-24-2020).]
A sensor is sending bad information to the computer. Are there any leaks in the exhaust system? The O2 sensor may be working, but picking up bad information.
No leaks from what I can tell, and I mean it could be faulty o2 sensor I replaced it and it had right readings?
The 2.8 O2 sensor is the single wire type. So it's ground in the exhaust piping its screwed into. The exhaust is bolted to engine. Engine has several ground straps to body and chassis and they like to break over time. Pick up some 1" braided ground straps long enough to connect from engine block to car body and chassis.
Plan "B". Use a cheap $8 multimeter from Harbor Freight and check for resistance Ohms between body of O2 to engine and then to car body. The lower the reading the better.
------------------ "Kilgore Trout once wrote a short story which was a dialogue between two pieces of yeast. They were discussing the possible purposes of life as they ate sugar and suffocated in their own excrement. Because of their limited intelligence, they never came close to guessing that they were making champagne." - Kurt Vonnegut
Tomorrow imma cut the cat out and temp replace it with a straight pipe, will probs get a high flow one in the near future and see if that fixes the issue and then I'll add more grounds I already went through and redid some and cleaned some others
[This message has been edited by Monkeybean007 (edited 03-26-2020).]
Alright update, replaced the Cat and it helped a ton the old one was super clogged so that was definitily needed , the reddevil cable will be here tomorrow and I'll use that to hopefully figure out whats going on as it still has the issue, while it's not as significant now.
Ya it's pretty frustrating but with this new found amount of free time that I currently have I have lots of time to work on the fiero,and it's also allowing me to get more used to the fiero, and where everything is located in the car so that's a plus. It's giving me time to fine tune some stuff, gonna get some new seats too just all the stuff lol. After I fix the car and get it running how it's supposed to be of course.
[This message has been edited by Monkeybean007 (edited 03-30-2020).]
I hear ya. All of our cars are detailed, drawers and closets have been cleaned out. Cleaned the windows, all the floors. Running out of things to occupy my time lol.
So I got the aldl cable and got all the readings but now I have nothibg to compare what it should be or shouldn't be, checked the user manual nothing and checked the Hayes manual and nothing as well, it did let me know none of my sensors have failed dosent mean they're not bad though.
And I'm gonna do some heavy detailing after I get the car running correctly, she needs a good buff 😂
So everything I have done I have posted in here, and yes issues once it warms up, did find out I didn't have a thermostat so go tone of those but all that affected was my tempeture gauge moving up and the engine actually being allowed to heat up, I did burp it correctly with a list from Patrick, it's still having the slow/choppy acceleration, I'm thinking it has to be a fuel air issue as all sensors from what I can tell have either been replaced now and are working correctly, checked for vacuum leaks none that I could find, redid a ton of grounds as well as adding some grounds, cleaned the ecm grounds as well.
