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Strange Prolem. Looking For Advice.

SandalsBoy

By SandalsBoy,
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SandalsBoy Enthusiast

SandalsBoy

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Hoping someone can help...

I own an 89 GTR. Clutch (OS twin plate) recently died, thrust bearing on the way out and friction plates all but wore out. Took it to the local workshop to have the gear box out. Took me a week to source a new clutch (Xtreme single plate). The workshop installed the new clutch... it works fine. however ever since the workshop put the gearbox+clutch back in, the car now blows black smoke and wont idle without stalling...

Had no other work done to the car besides the clutch... and everything was fine before i took it to the workshop...

IDEAS? Are there any vaccuum hoses near the gear box that could have been knocked loose? Im at a loss as to what it could be... and so is the workshop.

Thanks for your help in advance.

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doo doo Proficient

doo doo

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Posted (edited)

Def sounds like a vac hose has been taken off, however I can't think of any you need to take off to do the box. Check what you can see (try the vacuum feed to the clutch master cylinder- maybe they did a bleed and took this of?) and check spots like this to see if any thing has been broken rocking the engine back. Are you sure they can't remember what they might have taken off? If you're in Brissy I'd be happy to have a quick squiz- just had the engine out so have a good recollection where the lines under the inlet manifold and around the back of the head are.

Edited by doo doo
SandalsBoy Enthusiast

SandalsBoy

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Def sounds like a vac hose has been taken off, however I can't think of any you need to take off to do the box. Check what you can see (try the vacuum feed to the clutch master cylinder- maybe they did a bleed and took this of?) and check spots like this to see if any thing has been broken rocking the engine back. Are you sure they can't remember what they might have taken off? If you're in Brissy I'd be happy to have a quick squiz- just had the engine out so have a good recollection where the lines under the inlet manifold and around the back of the head are.

Thanks for the reply. Thats a very generous offer much appreicated! :) Unfortunately im in SA :P . I havent got the car back yet Ill be going down the work shop tomorrow to talk about what we gonna do. Any other possibilites (besides a vaccum hose?)

Edited by SandalsBoy
SandalsBoy Enthusiast

SandalsBoy

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Problem solved: The workshop has spent the day checking and they said that the "tuning" somehow changed. They couldnt explain how this happened by them taking out the gearbox.

Im not even sure how they made the "corrections" to the tuning that they claim they made... because i thought it was all controlled by the ecu... but i thought id post my very poor explaination for a fix in case it helps someone else. Perhaps someone better educated on these matters can add to it for the next person.

Thanks again do Doo Doo for posting :)

SandalsBoy Enthusiast

SandalsBoy

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PROBLEM NOT SOLVED!!

Ok, so the problem was supposedly fixed. The "tuning" that they were talking about to fix the problem was moving to TPS. Leaning it out a bit.

Went to pick up the car from the workshop today. When i got there, they started it up to show me. Was fine no smoke no idle problems.

I paid the bill, took the keys, got back into the car, started it up, problem is back.

They moved the TPS futher. Idle stabalized. Turned off the car. Started it again still ok.

I drove it home all was fine until i turn the car off and out of curiosity tried to start again...

Problem is back.

Any ideas what could be causing this? It seems like moving the TPS has just compensated for another underlying problem... im thinking....

AFM?

O2 Sensor?

Any other ideas?

Edited by SandalsBoy
doo doo Proficient

doo doo

Posted
Posted (edited)

So it's not running rich at idle? Have you tried re-setting your idle control?

Turn car on, reach under rear half of inlet manifold and disconnect brown clip off acc box (It's facing rearward), on the front side of this little box is an idle adjustment screw (phillips head), unscrewing outward will bring your idle up, when it's on 900 rpm plug the acc plug back on, idle is reset. Let us know if this fixes the prob. I would also imagine if you're TPS didn't need adjusting it should probably go back to where it was.....

Quick addition. Why did they give you a bill to fix a prob that they seemed to create? And is still not sorted? Unless they can justify to you it was something that was already there, but if the "fix' is band aid style (adjusting TPS) I'd be like hmmmm.....

Edited by doo doo
SandalsBoy Enthusiast

SandalsBoy

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Thanks for the reply :down:

I suspect it is running rich at idle ... because it wont idle. The car constantly splutters and it will stall pretty much straight away if the throttle isnt depressed. When the throttle is depressed its very rough and blows blackish smoke.

Because it wont idle i assume there is no point in resetting the idle, because it wont idle?

Oh and didnt pay for it to be fixed. Paid for the gearbox out/in.

Any more ideas?

SSHatch Collaborator

SSHatch

Posted
Posted

Still going with vacuum leak somewhere or

check the wiring to the O2 Sensors. See if its still plugged in or if its been damaged in some way.

Check the breather lines on the rear of the rocker covers. Could have been broken when the engine was laid back to remove the transmission.

Just trying to think what else is around the back of the engine that may have been damaged while the box was being removed.

I would be grabbing a torch and just eyeballing each wire and tube along their full length and checking for breaks in wires, wear marks that could be shorting or vacuum lines that may have been pinched or split accidentally.

SandalsBoy Enthusiast

SandalsBoy

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Hrmm had a look couldnt find anything. Ill keep looking, anything specific that people can think of that could have been damaged when taking the box out? As always thanks.

Still going with vacuum leak somewhere or

check the wiring to the O2 Sensors. See if its still plugged in or if its been damaged in some way.

Check the breather lines on the rear of the rocker covers. Could have been broken when the engine was laid back to remove the transmission.

Just trying to think what else is around the back of the engine that may have been damaged while the box was being removed.

I would be grabbing a torch and just eyeballing each wire and tube along their full length and checking for breaks in wires, wear marks that could be shorting or vacuum lines that may have been pinched or split accidentally.

doo doo Proficient

doo doo

Posted
Posted

Here's an attachment of a schematic of the vacuum lines. Hope it helps a little. Have you any lines in the cabin under passenger feet (like boost controller) that someone could have stepped on? The diagram doesn't include bov lines, but you'll see what runs behind the head.

Picture_clipping_4.zip

SandalsBoy Enthusiast

SandalsBoy

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Argh. still cant find any leaks or pinched wires. (nice idea about the in cabin lines :P but no, dont have any)

Its gone back into the workshop. Time to start working through the possibles...

AFM?

O2 sensor?

Here's an attachment of a schematic of the vacuum lines. Hope it helps a little. Have you any lines in the cabin under passenger feet (like boost controller) that someone could have stepped on? The diagram doesn't include bov lines, but you'll see what runs behind the head.
SandalsBoy Enthusiast

SandalsBoy

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OK Update time:

Changed over the AFMs with known working ones... didnt fix.

Changed ECU... bingo... working.

Gonna monitor for a few days and make sure the issue doesnt return...

Question is, how does taking the gearbox out kill the ECU? Or was it just a crazy concidence...

Work shop reckons it might have happened when the battery was disconnected/reconnected during the gearbox removal.

What do you guys think?

Edited by SandalsBoy
SandalsBoy Enthusiast

SandalsBoy

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Another update. The original ECU was sent off to get checked... came back as "its fine. no faults"...

Put the original ECU back in... problem has dissappeared. WTF???

Can anyone explain this? the workshop says the didnt change anything else... Is there something that might have "reset" when the ecu came out to have fixed the problem??

Edited by SandalsBoy
jeffworld2 Veteran

jeffworld2

Posted
Posted

i would get base timing checked now, while it is runnig well, and put your cas back where it is supposed to be and reset the ecu again.

i would say the ecu had pulled up an error with the idle control unit or afm and wasnt checking it again for whatever reason. if it wont idle, either it isnt getting an air signal or it is getting some that is unmetered ie serious vacum leak- cooler pipe off type stuff.

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