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 Post subject: Trouble Code Mystery
PostPosted: Sat May 17, 2008 8:22 pm 
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Hi,

I'm having trouble, codes and mystery with my Pontiac Firebird 3.4, 1994.

The problem appeared in summer last year, a few weeks after exchanging the motor block with a used one which ran only 55.000 km (the old was blown due to broken cylinder gasket and coolant loss). A few weeks after block exchange and running fine, the engine showed "check engine light" and a trouble code for the first time. Code listed a defect of the EGR. Thus, EGR was exchanged. One week later the same trouble codes and problems with oxygen sensor came up. In January the engine stalled during start. Further trouble code analysis yielded trouble with again EGR, oxygen sensors (both sides). Further diagnosis yielded (really!) fouled plugs (which already were exchanged with the new block 5000 km before) and a broken plug wire. Now, both oxygen sensors, all plugs and the broken plug wire were exchanged. The engine now starts normally, first seemed to run fine. A few days and 80 km later, the problem came up again. Perhaps, I have a slight impression of less power when reaching normal operating temperature and fast increase of temperature at idle shortly after running a few miles with moderate speed. However, no water or coolant loss is detected. Oil and coolant are fine.

The problem doesn't appear at low speed (eg. driving in city traffic). However, "check engine light" and codes appear when dropping speed after a few miles or a few minutes running at constant speed between 80 and 140 km/h and motor reached normal operating temperature. I would say codes appear immediately after having left last throttle position and before having reached the break pedal.

Trouble codes listed, so far:

13, 44, 63, 77

Ok, it is saturday and everybody laughing about choosing the wrong numbers in lotto. But, this does not appear to be my problem. :D

Is seems impossible, that all exchanged parts have the same defect again after 50 miles running, isn't it?

What might be the real problem here?

Please help!

Thank you in advance for your assistance.

Thilo


Last edited by fb94 on Sat May 17, 2008 9:47 pm, edited 1 time in total.

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 Post subject: Re: Trouble Code Mystery
PostPosted: Sat May 17, 2008 9:25 pm 
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Was it a stock replacement block? Has any tuning been done with the computer?

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 Post subject: Re: Trouble Code Mystery
PostPosted: Sat May 17, 2008 9:52 pm 
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Chevroletfreak wrote:
Was it a stock replacement block? Has any tuning been done with the computer?


Stock 3.4l V6 (SFI) block, no tuning done with either computer or machine, no different air filter, nothing. Is suspect, you expected engine and computer not matching, isn't it?

Unfortunately different sources give different answers about the true meaning of the trouble codes. Maybe, the nature of the problem will be a result of the interpretation of the combination, or not. Has anybody seen this problem before?

One of the codes may also be interpreted as a fault with the MAP sensor or vacuum. I now have a collection of used MAP sensors here and will give it a try. If you have different suggestions, pls. let me know.

BTW: What does it mean, if the air condition does not switch to blow its air in direction to the passengers seat, but only to front window and floor? Is there any coherence with vacuum problems and engine misfire like it is with older firebirds?


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 Post subject: Re: Trouble Code Mystery
PostPosted: Sun May 18, 2008 5:56 am 
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DTC - 13 Oxygen sensor circuit open or no activity

DTC - 13 Left bank O2 sensor circuit open or no activity

DTC - 44 Oxygen sensor error (lean condition indicated)

DTC - 44 Left bank O2 sensor error (lean condition indicated)

DTC - 63 Right bank O2 sensor circuit error

DTC - 63 MAP sensor circuit signal voltage high (low vacuum indicated)

DTC - 77 Digital EGR solenoid #3 circuit error

This is not uncommon when an engine is swapped in a vehicle . First time Mechanics will forget to ensure all wire connectors and vacuum lines are separated prior to removing the engine.
I would run continuity checks with a wire schematic in hand along with using a good GM workshop manual.

Inspect all connectors for damage and proper pin tension.
Ensure all engine to chassis grounds are in place and connected .

Your AC problem could be linked with your map sensor and 02 sensors ( low vacuum). Low vacuum will cause a lean condition which your O2 sensors detected.
Check and recheck for vacuum leaks , especially at the HVAC connection.

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 Post subject: Re: Trouble Code Mystery
PostPosted: Sun May 18, 2008 11:10 pm 
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Hi Roy,

Thank you for your assistance.

Roy wrote:
First time Mechanics will forget to ensure all wire connectors and vacuum lines are separated prior to removing the engine.


I didn't exchange the engine by myself. This has been done in a workshop.

However, as it sounds, the vacuum problem might be a possible reason for the engine damage before, because may problems start to sound smilar now. Maybe the real problem still exists and is located elsewhere. I'll check the lines again. Do you know where the EVAP canister is located on a V6? "Chilton" doesn't give an answer to me. Looked around my car, but didn't find the beast... However, it smells like fuel at the left rear wheel.


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 Post subject: Re: Trouble Code Mystery
PostPosted: Mon May 19, 2008 5:20 am 
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Thilo
I was kinda hinting at the shop that did your motor wechsel. I could not tellyou where your EVAP is at . But some good Google searching might pullit up.

For the moment I would pinch a vacuum hoses going through the engine fire wall and try to lcate that possible vacuum leak.

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 Post subject: Re: Trouble Code Mystery
PostPosted: Thu May 22, 2008 8:22 am 
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Roy wrote:
Thilo
I was kinda hinting at the shop that did your motor wechsel.


Not quite sure, what you want to tell me here.
Yes, I just tried to leave my car in a workshop before very often. But this kind of problem seems to hide itself against my favorite mechanics (until the old block was blown).
Bang away at my workshop definitely will not solve my problem. :D

I guess, I'm searching for a problem which might have caused my old engine broken, which nobody has found so far and still persists even with the new engine.

Thus, I prefer to have a solution for that. 8)

Well, I shall note, that we exchanged the computer a few years ago. So, I would prefer not to suspect the electronics here. Perhaps, reading carefully my symptoms written above, somebody will get an idea where to look, where we didn't look before.

In the meanwhile I'm not sure whether we really have a vacuum leak. Otherwise it would be there, sometimes not. Opening the fuel filler cap after driving, one hears "pfffft". So the evaporation seems to work and vacuum seems to persists, unless my air condition will not work in any case. But this is a different thing and might be a problem with the mechanics of the air vent.


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 Post subject: Re: Trouble Code Mystery
PostPosted: Thu May 22, 2008 10:03 am 
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Thilo
3.4L V6 engines are notorius for blowing head gaskets if coolant is changed per GM instructions. That is a given with the permanent antifreeze not being exchanged on a regular basis.

Also your A/C controls are all operated by Vacuum. So if the controls are not working correctly suspect a vacuum leak or bad vacuum control motor.

The trouble codes you show have associated trouble shooting procedures that will help in the isolation procedures.

You really need a good GM shop manual if you want to do that.

Reading wire schematics and diagnosing circuits is something that comes natural for me. Perhaps if you were close
I could take a look at it.

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 Post subject: Re: Trouble Code Mystery
PostPosted: Thu May 22, 2008 8:17 pm 
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Roy,

Thank you.

Perhaps your hint of the double meaning of the codes with MAP sensor high and/or indicating a vacuum leak pointed to the right direction.

Today I rolled the Fbird from my garage to exchange the MAP sensor by a different one to check its functionality. To access it more convenient, I removed the EGR valve to access the MAP sensor and to check the gasket of the EGR. The gasket which comes with the EGR is a part, which one shall care about. Although I carefully removed rust from the surface where the EGR is mounted, the surface seemed rough enough, maybe the EGR gasket seemed to leak after months. I removed the gasket completely and replaced it using high temperature silicone gasket. After a couple of hours I carefully started the engine. My code scanner showed the EGR and MAP working on the road with no new codes. The old MAP seemed to run out of tolerance in some situation, even if I cannot see a big voltage difference.

I shall keep my fingers crossed...

Roy wrote:
Thilo
3.4L V6 engines are notorius for blowing head gaskets if coolant is changed per GM instructions. That is a given with the permanent antifreeze not being exchanged on a regular basis.


Not to say, the problems with my old engine started after a regular inspection with changing the coolant. :(
Which antifreeze would be the best? As with my experience, usual antifreeze from GM specs will produce rust in coolant, if the engine reached a certain age. My 1998 Olds Silhouette minivan has a red antifreeze. No problems with rust within a 3.4l V6 engine (~200hp). Will the red one be an option for the 3.4l SFI engine of the 1994 Fbird?


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 Post subject: Re: Trouble Code Mystery
PostPosted: Fri May 23, 2008 3:30 pm 
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Well, here they are again... my codes. :(
After a short trip on the highway, again I found them completely and none of them is missing: 13, 44 63, 77

Think I'll give it up. It starts to be more expensive than having fun.


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 Post subject: Re: Trouble Code Mystery
PostPosted: Sat Aug 30, 2008 11:10 pm 
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Finally good news: the problem has been solved.

First to say, I decided to see which part will give up next. And, yes: the battery faulted four weeks ago. I was not able to reload the battery, although it showed not beeing broken. I took my Oldsmobile, went to Mike & Franks an bought a new one. After that the behaviour of the engine and power felt completely different. Unfortunately, one day later, I saw problems again. I noticed the alternator was broken. The charge level of the battery was below 12V as seen from the dashboard, the power dropped again the engine heat increased and the engine shuttered. The new battery was not charged completely and voltage was speed dependent. I stopped and drove to my workshop. We exchanged the alternator by a new one. This didn't help enough and any possible error code came up again after fixing the broken alternator.

Finally I exchanged the PCM module.

After doing all this, the trouble code 77 came up again with heavy acceleration at the first ride on the road. This happened after a kick down, overtaking another car and cut off the engine (dropping gas, no break, the error occurred after a few seconds). We were discussing the error, as it cannot occur within this situation. The error indicates a problem with solenoid 3 of the EGR valve. As seen from my autoscanner the valve is definitely closed (EGR valve off) at the speed where the error occurs. And this valve is closed with dropping gas or no gas anyway. So there is no reason to have any indication of an error caused by a broken solenoid (at least with my new EGR valve).

I decided to simply ignore and reset the error code, give it a try and drive the car like it would be a brand new car over a distance of a few hundred kilometers. Since that the car now runs fine and much different that before. Compared to the power noticed before it feels like having 200 hp. Testing the machine on the highway with only half gas it accelerates up to 180 km/h. Dropping gas now is not a problem, like it was seen by the error codes shown before.

We tested the PCM with another fbird and found, it seems definitely broken. Any error code found before with my car showed up with only a few kilometers on the road within city traffic.

Some guys told me some errors and characteristic field may be burned into the PCM after a while, if an error will not be fixed soon. Sorry, but I cannot give a definite confirmation to this from my electronic understanding. It more or less seems that a couple of things lead to a faulty PCM: faulty alternator, faulty battery and ... whatever the PCM thinks to be a reason due to power failure. From my understanding, the PCM maybe seemed to calculate new characteristic fields for that engine, which might explain fowled spark plugs and broken oxygene sensors. What do you think?

Nevertheless, the 14 years old car is back on the road again. Tell you, very different feeling. It is able to overtake others again. :-)


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 Post subject: Re: Trouble Code Mystery
PostPosted: Sun Aug 31, 2008 6:25 pm 
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That sounds like a classic case of moisture causing corrosion on the PCM terminals or on the PCM board it self.

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 Post subject: Re: Trouble Code Mystery
PostPosted: Sun Aug 31, 2008 10:41 pm 
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Roy wrote:
That sounds like a classic case of moisture causing corrosion on the PCM terminals or on the PCM board it self.


Terminals were ok. PCM was exchanged earlier and about 4 years old.


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