Running rough
Printed From: West Coast Fieros
Category: Technical Topics Forum
Forum Name: Technical Questions and Discussions
Forum Description: Got a technical question about your fiero? ask it here.
URL: http://www.westcoastfieros.com/forum/forum_posts.asp?TID=2554
Printed Date: 23 November 2024 at 8:17am
Software Version: Web Wiz Forums 12.01 - http://www.webwizforums.com
Topic: Running rough
Posted By: D_sensitized
Subject: Running rough
Date Posted: 01 July 2011 at 11:37pm
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So my fiero has been running a little rough lately, though intermittently.
Yesterday it was stumbling whenever I gave it some gas on my way home from work. Checked all the plugs and wires and it all seemed fine. SES light was on though and I don't have a scantool. Driving out to Langley yesterday was perfectly fine with no issues. Today driving to the fireworks was fine with no issue but returning home it felt like it was weaker and revs would fluctuate at steady throttle. The SES light was on again as well and after about 20 minutes of city driving when I looked in the engine bay the manifold was glowing a little. For a while now it's had some stumbling on throttle but not on every drive. The SES light would occasionally come on when I start the car but if I shut it off and start it up again it's fine. I've had codes involving the o2 sensor in the past so would a dead/dying sensor cause these problems or could it be something else? I'll still be at autoX tomorrow so if someone there could help diagnose things it would be good. Unless it decides to run trouble free. I will try to take it somewhere to read the codes this week, otherwise does anyone have a code reader that will read obd 1.5? This is in my 3800 sc1 swap in 88gt. Motor from a '95 olds 88 ------------- -Harrison 88GT 3800 SC1 F23 5-speed Chilliwack |
Replies:
Posted By: Dawg
Date Posted: 02 July 2011 at 12:29am
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Hmmm....glowing exhaust means running lean. Very bad! Fuel issues can cause this. Check pressure to make sure you're getting enough. When an engine light is coming on and off I always suspect the oxygen sensor. Other sensors tend to go out of range and stay there. Oxygen sensors can fluctuate. My gut says check fuel first. Cheers, Dawg ------------- You dream it up....I'll make it |
Posted By: mxracer208
Date Posted: 02 July 2011 at 12:02pm
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I've got a very similar problem, only I have the 2.8. My
exhaust doesnt glow though |
Posted By: D_sensitized
Date Posted: 02 July 2011 at 6:20pm
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The fuel pump builds pressure when I turn on the ignition, pump stays
on for a few seconds. Speedo sometimes twitches as well, didn't work at all last night driving home, sometimes it jumps when I'm just sitting there idling. Was still rough this morning at autoX but the afternoon was all fine. I picked up an o2 sensor on my way home so I'll try that and see if that is the problem. ------------- -Harrison 88GT 3800 SC1 F23 5-speed Chilliwack |
Posted By: D_sensitized
Date Posted: 05 July 2011 at 4:37pm
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Well I replaced the o2 sensor with a new one, and it is now worse
than before. It stalled on me on my way to work this morning and was really hiccuping quite a but. At points the throttle would just make it stutter instead of rev up. It idles fine and in park it is usually ok but occasionally stumbles when I open the throttle. Could this be a vacuum leak or bad tps or air sensor? It's quite intermittent but has been getting worse the past few days. Hasn't thrown any codes other then once when it actually stalled. ------------- -Harrison 88GT 3800 SC1 F23 5-speed Chilliwack |
Posted By: Patrick
Date Posted: 05 July 2011 at 6:11pm
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Not sure how that would help.
A vacuum leak would cause a high idle. The TPS isn't too difficult to check. It should have a variable (up or down) reading as it opens, sort of like a variable resistor. You don't want a "dead" spot. Not sure what an "air sensor" is? Is that a MAF sensor? Part of the problem with getting advice here is that many of us know nothing about the 3800. I could suggest you check the MAP sensor, but that engine may not even have one. Harrison, do you post at Pennock's? There are probably a hundred guys there who could offer advice on your engine/Fiero.
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D_sensitized wrote:
Posted By: D_sensitized
Date Posted: 05 July 2011 at 9:31pm
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I will try to test the TPS tomorrow. When idling, if i blip the throttle a little bit, it will sit around 1000-1200 for a few seconds before coming back down to normal. I think its the MAF sensor it only has one of the MAP/MAF sensors and I always get them mixed up. it's in the throttle body if that helps. I go to pennocks every now and then so maybe I will ask there. ------------- -Harrison 88GT 3800 SC1 F23 5-speed Chilliwack |
Posted By: Bassman
Date Posted: 05 July 2011 at 9:54pm
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Cool:) ------------- Brian (Bassman) 86 GT Fastback 3.2L 2013 Mazda3 Sport GS SkyActive [IMG]http://i170.photobucket.com/albums/u243/Bassman68/BassmanSignature.png"> |
Posted By: D_sensitized
Date Posted: 06 July 2011 at 12:18pm
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Oops, I meant that I fixed the u2/o2 typo. I can see how that would be
confused lol. I put clamps on a couple vacuum lines that felt a little loose and it feels like it's running slightly better, but still not fixed. I'll try to trace any vacuum leaks and fix those if there are any. ------------- -Harrison 88GT 3800 SC1 F23 5-speed Chilliwack |
Posted By: D_sensitized
Date Posted: 06 July 2011 at 10:28pm
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I think I found what it could be! Or at least I found something that needs fixing.
There seems to be a vacuum leak in the charcoal canister(?) the one next to the air box. I can hear it hissing and when i pinch the lower line, it goes silent the the idle jumps up for a couple seconds. (from around 600 to 900 then slowly back down) Does anyone have a spare canister they would be willing to part with at the meeting? ------------- -Harrison 88GT 3800 SC1 F23 5-speed Chilliwack |
Posted By: Patrick
Date Posted: 06 July 2011 at 10:55pm
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I can give you one.
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Posted By: D_sensitized
Date Posted: 12 July 2011 at 4:59pm
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Well whatever I try to fix, just seems to make things worse. replacing the canister did nothing, blocking off the lines to the cruise control and canister made it worse, putting them back on didn't make it better.
Can keep an idle, but anything between that and 3/4 throttle will sputter and the revs would jump around from 500-2000 randomly, occasionally die, then pick back up again. Brakes seem a little harder to push sometimes which makes me think it's still a big vacuum leak somewhere, but I could just be imagining it. Tonight I plan on going through each and every vacuum line and connection to try to find something. ------------- -Harrison 88GT 3800 SC1 F23 5-speed Chilliwack |
Posted By: D_sensitized
Date Posted: 20 July 2011 at 4:50pm
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Well, still havent figured out the problem. I found one cracked vacuum
hose and replaced it but it's still not better. It usually has trouble when I first start it up in the morning and after work and is really struggling and stuttering as if it loses power for a split second, then after a minute or 2 it drives fine. Just a couple hiccups here and there once I've started driving but nothing big. The speedo also flies around sometimes when the engine stumbles and sometimes just on it's own. This morning was the worst, ran so terribly it died after a minute or 2 and on the third try, stayed running and went on as normal with a bit of stuttering as I drove off. Only time the SES light came on was when it couldn't stay running that one try this morning. Gonna try to take it to the shop tomorrow and see what the scanner has to say. ------------- -Harrison 88GT 3800 SC1 F23 5-speed Chilliwack |
Posted By: karnak
Date Posted: 20 July 2011 at 10:24pm
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Hmmm....have you looked to see if the timing is advancing during
accel? If it isnt then the motor cant really speed up properly...leading to crank or speed sensors (that sort of thing) that tells the ecm that something is happening. Not sure about the 3800. The distributor would do that in a stock motor. Could just be a wire or plug at the distributor. Can you also disconnect the MAF to cause it to code out and run a default value to test it? Good luck! Gary |
Posted By: D_sensitized
Date Posted: 22 July 2011 at 3:39pm
It just keeps getting worse 
Am currently waiting for a towtruck on the side of the highway. Was able to drive for a little bit and then it would get quite rough and all throttle response would go down to zero and I would have to coast to a stop before the engine finally cuts out. Will look up the procedures and test as many sensors as I can to see if it's one of those, otherwise I suspect it to be wiring, in which case I will probably take out the whole harness and inspect it all. ------------- -Harrison 88GT 3800 SC1 F23 5-speed Chilliwack |
Posted By: Colby
Date Posted: 22 July 2011 at 3:44pm
 I hope you're able to figure this out.
------------- 88 Formula 5 speed |
Posted By: D_sensitized
Date Posted: 22 July 2011 at 5:52pm
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Unplugged and plugged back in the MAF sensor and it coded, so I
assume it's working. O2 sensor is new so that should be fine. Backprobed the throttle position sensor and got 4.6v at closed and .888 at wide open. Are these values ok? Smells like it's running rich as well so there's too much fuel going in. Shop was too busy this week so I couldn't get a scanner on it. Another thing is at idle, when revving up to around 3k, the speedo will go up to around 10 km/hr when I'm sitting still. Thats all I have time to do tonight, Sunday I will get more time to dig into it. ------------- -Harrison 88GT 3800 SC1 F23 5-speed Chilliwack |
Posted By: Dawg
Date Posted: 22 July 2011 at 7:39pm
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To my knowledge, the speedo and tach circuits are not interconnected other than they use the same power source. So my guess is you have a wiring issue, meaning you have two unshielded wires close together that shouldn't be. This could induce just enough tach signal into the speedo line for it to react. Try tracing the tach signal back to it's source and then disconnect it. Then do the rev up thing again and see if it's better. If that works, then you need to separate that wire from the speedo signal coming from the tranny. Also, does your stereo whine while you're driving? This might mean you have dirty power coming from your alternator. It's possible that really noisy power could confuse the speedo circuit. Other than that I don't know. The Dawg
------------- You dream it up....I'll make it |
Posted By: Dawg
Date Posted: 22 July 2011 at 7:50pm
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You know.....I just went through your whole thread and it really seems like it's timing to me. Like you're totally loosing timing for short periods of time. I would check your crank sensor. I bet it's buggered. The Dawg ------------- You dream it up....I'll make it |
Posted By: Colby
Date Posted: 24 July 2011 at 11:04pm
So, did you find anything? ------------- 88 Formula 5 speed |
Posted By: D_sensitized
Date Posted: 25 July 2011 at 6:48am
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Took out the whole harness and inspected all my wiring, apart from
some toasted coolant sensor wires which were still fine, everything was ok. After reading around a bit more on the Internet and from what Dawg said, I think it's the crank sensor. So today I'll have to get a new pulley puller and sensor so I can replace it. Hopefully that's finally it. ------------- -Harrison 88GT 3800 SC1 F23 5-speed Chilliwack |
Posted By: Dawg
Date Posted: 25 July 2011 at 11:06am
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There are ways to test the sensor before you go out and just buy one. Are you made of money or somethin'.....:) I've even heard of the external ones coming loose or getting really gunked up. Poke around in there before buying something you might not need. The Dawg ------------- You dream it up....I'll make it |
Posted By: D_sensitized
Date Posted: 25 July 2011 at 12:24pm
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Ya, I'll need the puller and to take off the balancer just so I can look at
the thing anyway. We'll see how tonight goes. ------------- -Harrison 88GT 3800 SC1 F23 5-speed Chilliwack |
Posted By: D_sensitized
Date Posted: 02 August 2011 at 9:08pm
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I fixed it! or at least I fixed that problem. Ended up being the crank sensor. Replaced it and it all ran fine... for a day.
Now it seems to like going into limp mode or something like that, no first or 4th gear. I can manually get it into first so that I don't have to rev the heck out of it to make it move from a stop, but that gets annoying. I did manage to pull codes on my way home. A heated o2 sensor code which is probably just wiring, since its a new sensor. And code P1650- QDM2 failure. Not sure exactly what that means but it seems to be whats causing me problems. I replaced the ECM to no avail. I have a printout of a couple methods to go about trying to fix it but wont have time until the weekend by the looks of things. On a side note, I finally got around to installing Rodney's lowering ball joints I have had since march. ------------- -Harrison 88GT 3800 SC1 F23 5-speed Chilliwack |
Posted By: Bassman
Date Posted: 02 August 2011 at 9:12pm
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Nice to hear, hope to see you out soon...and really intersted in those ball joints and how they work out for you...
------------- Brian (Bassman) 86 GT Fastback 3.2L 2013 Mazda3 Sport GS SkyActive [IMG]http://i170.photobucket.com/albums/u243/Bassman68/BassmanSignature.png"> |
Posted By: Colby
Date Posted: 02 August 2011 at 11:31pm
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Do you think you'll be able to get it working properly before the event on the 7th?
------------- 88 Formula 5 speed |
Posted By: Dawg
Date Posted: 03 August 2011 at 11:26am
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I too am interested in your balls.....wait....that didn't come out right..:) The Dawg ------------- You dream it up....I'll make it |
Posted By: D_sensitized
Date Posted: 04 August 2011 at 8:02pm
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Well it won't be done in time for the 7th.
I can't say much about the ball joints since it's only been running properly for a few minutes since then. But it has leveled out the car and got rid of the high front 88s seem to get. Still trying to solve my current issue, code P1650-QDM2 failure. Need a scan tool to properly test things on the computer side, but replacing the ECM did nothing. Wires seem ok so the other possible culprit would be a bad shift solenoid. Will have some more time to try to look into it further tomorrow evening. ------------- -Harrison 88GT 3800 SC1 F23 5-speed Chilliwack |
Posted By: Patrick
Date Posted: 04 August 2011 at 8:38pm
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Colby! Calling Colby! Harrison, which lowering ball joints are these? (as Rodney sells two different ones, 1/2" and 1")
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Posted By: Colby
Date Posted: 04 August 2011 at 9:53pm
I've looked into them. They need a 15" rim or larger and I'm not prepared to throw away over $500 worth of tires and rims just for that. ------------- 88 Formula 5 speed |
Posted By: Patrick
Date Posted: 04 August 2011 at 9:59pm
I wasn't necessarily promoting the lowering ball joints. I was just making reference to... "the high front 88s seem to get".
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Posted By: karnak
Date Posted: 04 August 2011 at 10:47pm
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Sand bags in the front can do the same thing... try it at the next autox
Colby 
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