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92 firebird rpm issues


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logan7221
User

Feb 16, 2014, 6:12 AM

Post #1 of 19 (1477 views)
92 firebird rpm issues Sign In

I purchased a 92 firebird automatic about a 2 weeks ago and at first everything was fine but now I seem to be running into some issues. The first problem is when I let off the gas for a while and coast the rpms will jump up and down by about 500, so it will go from 500-1000. Everytime this happens the car jerks forward as if Im slightly hitting the gas. The oil pressure guage is another issue it has and seems to fluctuate. It will be nearly to the red line then suddenly jump back up to normal and I mean a sudden jump. it also on occasion seems to have acceleration problems. If I slam on the gas it accelerates at a decent pace but out of nowhere it acts like it gets a huge flow of gas to the engine and it takes off. It doesn't seem to have any shifting issues and does so smoothly. Any idea what this could be? Im thinking maybe a vacuum leak perhaps? I honestly don't really know and that is simply my best guess but other than these issues the car runs just fine. Oh and sometimes when I try to start it I just get a knocking sound coming from the starter. I picked up a new starter but have yet to replace it as I'm kind of waiting for the snow to melt a bit.


(removed hyperlink from another site)


(This post was edited by Tom Greenleaf on Feb 16, 2014, 6:56 AM)


kev2
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Feb 16, 2014, 7:03 AM

Post #2 of 19 (1454 views)
Re: 92 firebird rpm issues Sign In

first thoughts-
> which engine - 8th charactor of vin will tell if not sure
> Firebird - is this vehicle STOCK?
> 1992 - easy first step - get codes - even if light is off - get codes to ck system


let us know on starter change and that knock


logan7221
User

Feb 16, 2014, 3:36 PM

Post #3 of 19 (1433 views)
Re: 92 firebird rpm issues Sign In

its a v6 but not sure what size exactly and as far as whether or not its stock, your guess is as good as mine. I would assume it is but could be wrong. I will run codes with a paper clip to check system as I don't have an OBDI reader and neither does Advanced Auto. I did notice if I press the brake the rpms just shoot up once by about 500 then drop down to normal and stay there? TPS maybe or is a vacuum leak more likely? I got a 100 mile drive tomorrow and I doubt this will cause me any issues but just in case do you have any thoughts?

(Edit)It also does not do this while idle in any other gear than drive. Let off the gas and wait till the rpms drop down below 1k and the rpms start the jump cycle. So it pretty much only does this while coasting.


(This post was edited by logan7221 on Feb 16, 2014, 3:46 PM)


Hammer Time
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Feb 16, 2014, 5:48 PM

Post #4 of 19 (1429 views)
Re: 92 firebird rpm issues Sign In

If you can get the RPMs down for a second, unplug the IAC while the idle is down and then see how it acts. This will set a code but you can clear that.



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



Tom Greenleaf
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Feb 16, 2014, 11:33 PM

Post #5 of 19 (1423 views)
Re: 92 firebird rpm issues Sign In

You don't need a code reader just post the #s you get from the blinking CEL. About impossible if you don't even know what exact engine or alterations might have been done to it how are we to know?


T



logan7221
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Feb 17, 2014, 2:10 PM

Post #6 of 19 (1403 views)
Re: 92 firebird rpm issues Sign In

Ok, well I tried to get some codes but see no flashing when I cross a and b. Anyways, I changed out the TPS twice today. They both seemed to be faulty but I doubt this seeing as how the odds of getting two bad ones in a row are slim to none. It did seem to correct the acceleration issue but the idle got worse. In park the rpms would sit at around 1500 and the surging after releasing the gas got worse to the point that it would continue after coming to a complete stop and not just do it once or twice.

EDIT: Also as far as I can tell it is a base 3.1 V6..


(This post was edited by logan7221 on Feb 17, 2014, 2:11 PM)


Tom Greenleaf
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Feb 17, 2014, 3:45 PM

Post #7 of 19 (1398 views)
Re: 92 firebird rpm issues Sign In

These were listed engines if normally plain new OE choices:
Available engines
  • 6 Cylinders T 3.1L MFI OHV)
  • 8 Cylinders 8 5.7L FI (found in 05% of 1992 Pontiac Firebird)

* 8 Cylinders E 5.0L TBI OHV (found in 90% of 1992 Pontiac Firebird)
  • 8 Cylinders F 5.0L FI (found in 05% of 1992 Pontiac Firebird)

********************
The letter designation will show in the vehicle's VIN #
There should be a sticker over the radiator as well with the data and info there too.
Reason for asking is most were 8 cylinders and someone may have messed with the car like take the "8" out or some fool thing like that but leave it a running car. No flashing codes or if light is blown or missing is kinda indicative it's been messed with. These cars more than most get messed with so you really need to know if at all possible.


TPS if you just get a clean change in OHMs from one it's about certainly good by itself. Can it communicate with the car is another thing and it might not?


You've just had it two weeks you said so need as much history as possible. I've seen so many get altered and messed with then beat to crap you at least need to know it if so.


? If you just unplug the TPS does it change anything? This could be a real goose chase if engine is altered or non OE for the vehicle,


T



logan7221
User

Feb 19, 2014, 4:07 AM

Post #8 of 19 (1380 views)
Re: 92 firebird rpm issues Sign In

Im pretty sure its a V6 as far as which I couldn't say. The guy I purchased it from didn't have a clue. It has 7 wires coming out of the distributor and I'm assuming the 7th is the lead in? According to the VIN it should be the V6 so I hope that's what I got. If I disconnect the TPS the rpms of the car just stay higher in park which is kind of what it does when I install the new tps the only difference is they go down when I put the car in gear but for some reason it feels like the throttle is stuck open somewhat when the new tps is installed and it rolls forward more when not pressing the gas.

For the hell of it I disconnected the IAC and that raises the RPMS up to about 2k and if I press the gas they get stuck at what ever rpms I left off when I release the pedal. Another thing I noticed is when I instal the new tps I have to twist it more to get it lined up with the bold holes unlike the old one and perhaps that's whats causing the issues? Wrong TPS perhaps as I see no way to adjust it?


Tom Greenleaf
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Feb 19, 2014, 4:59 AM

Post #9 of 19 (1376 views)
Re: 92 firebird rpm issues Sign In

The six was on the rare side for this. Lets find out what it is or we are wasting time. Best guess is it should be painfully obvious and marked like this one............

Another if OE may look exactly like this.........



Maybe not as the Firebird was RWD but until you are sure so much as trying with parts is futile,


T



(This post was edited by Tom Greenleaf on Feb 19, 2014, 5:01 AM)


logan7221
User

Feb 19, 2014, 5:56 AM

Post #10 of 19 (1367 views)
Re: 92 firebird rpm issues Sign In

Here's a few pics of the engine and some other things I haven't been able to figure out. The engine appears to be the same as the one you had in the second pic.




As of lately I've been hearing a rattling sound under the car toward the rear. Perhaps the muffler or something but I doubt this is even remotely related to the surging and acceleration issues. While changing the TPS I noticed there's a gash in a hose leading to what I believe to be the thermostat. Not deep enough to cause a leak but it's there....

(edit) I dropped the panel to change out the dimmer switch when I came across that box. Sadly it's missing the bar to actually hit the dimmer switch so that was another fail on my part. The dimmer switch wasn't bad but the bar was gone. The wipers don't shut off right either so that's another issue but I think I will order some parts for that.


(This post was edited by logan7221 on Feb 19, 2014, 1:58 PM)


Tom Greenleaf
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Feb 19, 2014, 6:42 AM

Post #11 of 19 (1354 views)
Re: 92 firebird rpm issues Sign In

OK - Looks like the OE engine so let's move on.
That button and rigged in stuff is probably some anti-theft device. How it's supposed to work and what it disables will be a mystery. You really need to take junk like that out and have everything original or it could be a factor in strange electrical problems. Couldn't guess what the original was if you don't have papers on that.


TPS whether the problem or not didn't seem to fit right you said. Hmmm? Wrong part? Not sure that's even a problem.


Perhaps the best thing to do is get the subscription for AllDataDIY which will have all kinds of info and diagrams at your beck and call for a year's subscription. It's old now which alone is fine but if you want this thing to be nice and run perfectly there will be an assortment of things to do ongoing.


Sorry to blame so much on the type of car as because it's based on the age old Firebird/Camaro set up they weren't for grocery getting or carting kids around so much but for the sport of them and many got altered. Old as it is IMO it's too new for messing with too much from OE designs for anything or it's a total headache.


Pics were real wide making the thread wide now and harder to read. No matter for now. I suggest you get as much info and history as you can muster OR the AllData if you wish to fix all the assorted things that a car that old is going to need here and there.


If into it enough, join a Camaro/Firebird club as well.


Can't look back but you need to find out about the CEL light not working and why. That's a problem high on the list to correct,


Tom



Hammer Time
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Feb 19, 2014, 7:04 AM

Post #12 of 19 (1350 views)
Re: 92 firebird rpm issues Sign In

I hope you have concluded that you definitely don't have a 6 cylinder. That is a V8.



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



kev2
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Feb 19, 2014, 7:28 AM

Post #13 of 19 (1347 views)
Re: 92 firebird rpm issues Sign In

4 days, @ dozen posts, color glossy photos, a debate, only needed the 8th character of the vin post #2- was that to simple?


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Feb 19, 2014, 7:42 AM

Post #14 of 19 (1346 views)
Re: 92 firebird rpm issues Sign In

Yeah, and now the thread is impossible to read with the oversized pictures. Please either reduce the size or delete them.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



logan7221
User

Feb 19, 2014, 2:05 PM

Post #15 of 19 (1329 views)
Re: 92 firebird rpm issues Sign In

The VIN is as follows 1G2FS33T1NL217367. According to the VIN the car is indeed a V6 like I said. I'm kind of confused after reading the post about it being a V8. I deleted some of the over sized pictures too as it wasn't my intention for them to turn out so large. They all should of been the same size as the engine pics. As for the tps not fitting properly, it does fit but not in the same way as the old one. The new tps has to be lined up then twisted to match up with the bolt holes which turns the knob on the tps.


Hammer Time
Ultimate Carjunky / Moderator
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Feb 19, 2014, 2:33 PM

Post #16 of 19 (1326 views)
Re: 92 firebird rpm issues Sign In

According to that VIN, it is a 3.1. The intake looked like it had 4 runners on each side but I guess that's not the case.
Thank you for taking care of the pictures. The thread is readable again.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



(This post was edited by Hammer Time on Feb 19, 2014, 2:34 PM)


Tom Greenleaf
Ultimate Carjunky / Moderator
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Feb 19, 2014, 10:37 PM

Post #17 of 19 (1312 views)
Re: 92 firebird rpm issues Sign In

All this so far. It was asked and staring at you......... Posted it..... see the "T" in this from earlier?


6 Cylinders T 3.1L MFI OHV)


Tom



logan7221
User

Feb 26, 2014, 5:35 PM

Post #18 of 19 (1273 views)
Re: 92 firebird rpm issues Sign In

Getting ready to actually do some work on this car next week sometime and I did manage to get the codes off and here they are as follows. It has a new tps so I'm not sure if that is an old code entry or from driving it with the TPS that I purchased which did not fit. Also drove with the IAC disconnected by mistake.

22-TPS sensor too low
33-MAP sensor or circuit high
45-Rich exhaust
44-Lean Exhaust
43-ESC module or sensor circuit problem


Discretesignals
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Feb 26, 2014, 6:50 PM

Post #19 of 19 (1270 views)
Re: 92 firebird rpm issues Sign In

You should disconnect the battery for 10 secs to clear those codes out. Then see which ones come back after taking it for a test drive. You may have set some of those codes unplugging things.





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