Car not running right after headgasket replacement

[jessevr4]

Okay so i've just replaced both head gaskets on my '98 Legnum and now that it's all back together it won't run properly. It turns over fine but won't stay running, if it manages to actually start it will run very rough and dies a few seconds after. It feels like it would if the timing was out, but it's pretty dead on. I've done compression tests just to check and each cylinder gets between 145-155psi. On pulling the plugs I noticed they are very black at the tip, not sure how normal that is considering I bought brand new ones while replacing the gaskets. I've also noticed that when I start it and I press the gas it will rev up but not come back down even after I get off the pedal. After it dies it will sometimes make a strange squeak noise like air being released from somewhere. I'm running out of ideas, and any help would be appreciated. Please ask if there's any more info I can include to help. Cheers, Jesse.

[hbkuk1]

Obvious but I would recheck everything you removed and then check it again

[Davezj]

Plus the ecu will have relearn idle conditions.
So the engine will normally find it hard to start for the first 5 or 6 times of trying to stat then it will get better and better.

If it is still not starting then yes check all the connection are made to the point of hearing the click as the connectors are mated up.


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[jessevr4]

Obvious but I would recheck everything you removed and then check it again

Yeah, I've done this a few times now but I'll check it again just incase it's something really stupid I've forgotten. What would cause the cars revs to not drop when the accelerator is let go?

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[Humpty's Revenge]

Yeah, I've done this a few times now but I'll check it again just incase it's something really stupid I've forgotten. What would cause the cars revs to not drop when the accelerator is let go?

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Accelerater cable to tight ?

[crazydriver81]

My first idea would be to check the ICV which sits below the TB. Is the plug seated correctly? This can cause the engine revs to stay up after hitting the acc pedal.

Other idea would be an air leak of some sort. Basicslly, if the engine dies it is either too much fuel or too much air which might indicate air leaks somewhere.

[jessevr4]

Accelerater cable to tight ?

Nah, I actually have it disconnected at the moment and just rev it using the peice on the throttle body

[hbkuk1]

Nah, I actually have it disconnected at the moment and just rev it using the peice on the throttle body

If this is disconnected it cannot move if its open it will cause too much air at idle therefore rev high if it's closed it will not be enough air and struggle to stay running you better off connecting it and letting it learn what it needs to do it will stall and generally be a pain until it sorts itself out. You can blank it off also and use the idle speed screws like in the old days too

[jessevr4]

If this is disconnected it cannot move if its open it will cause too much air at idle therefore rev high if it's closed it will not be enough air and struggle to stay running you better off connecting it and letting it learn what it needs to do it will stall and generally be a pain until it sorts itself out. You can blank it off also and use the idle speed screws like in the old days too

I disconnected it after I was having all these problems. Im sure it's not a problem of the ECU learning it's stuff back as I've done it before and it was nowhere near this bad. I had a go at just keeping on starting it, it started up and revved up to about 3-4k and held the revs then died, and now after a couple of starts it'll get to a certain point and the starter will just stop even though I'm holding the key on, like something is catching and won't let it turn over. Something is really wrong and I think I've ****ed something up.

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[jessevr4]

I probably should have mentioned this to start with but forgot, but when I was doing the timing to start with at the crank it was a tooth out when I tried to start it. I pulled the intake manifold off to try and get a look at the valves as best I could but couldn't see anything obvious, going to pull the exhaust mani off and have a look also (just trying to avoid pulling the heads again). How far would it need to be out to start bending valves?

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[hbkuk1]

One tooth won't cause contact, are you sure the rearmost cam is correct as on some 6a12/13 engines the rearmost cam does not line up with the mark exactly it's kinda half a tooth out so you maybe 1 tooth out there having said that I did this the first time I did it and it did not cause the issue your having it just felt flat no power. Have you checked all vac/boost pipes for damage/correct placement etc it's almost certainly going to be something like that

[jessevr4]

I looked up a vac diagram and made sure that the solenoids or whatever they near the intake are going to the right places, I'll have a look at all the other lines I can get to and check. Cheers for the help.

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[Davezj]

if the timing is off by one tooth you will have to take the belt off and do the timing correctly otherwise the car will not run as correctly.
i am not saying it is the idle issue you re experiencing but the timing has to be correct otherwise you will never get the best out of the engine.

a word of advice for the cam belt fitting.
painting the timing marks on the cam covers and the cam pulleys make alignment easier same applies to the crank.
when doing the timing belt you need to align all the cam shafts with the marks (use cable ties of bulldog clips) then set the crank shaft to the alignment mark and then move it one tooth back from the correct alignment. so when the belt it fitted and tightened the cam marks will line up with the crank marks.

one other general thing,
when posting on this forum particularly for diagnosis of an issue, we only know what you type we are not mind readers. don't be shy with detail of the issue.
the more info you give us, the better the diagnosis will be and the less questions we will have to ask to get the diagnosis correct.

[jessevr4]

if the timing is off by one tooth you will have to take the belt off and do the timing correctly otherwise the car will not run as correctly.
i am not saying it is the idle issue you re experiencing but the timing has to be correct otherwise you will never get the best out of the engine.

a word of advice for the cam belt fitting.
painting the timing marks on the cam covers and the cam pulleys make alignment easier same applies to the crank.
when doing the timing belt you need to align all the cam shafts with the marks (use cable ties of bulldog clips) then set the crank shaft to the alignment mark and then move it one tooth back from the correct alignment. so when the belt it fitted and tightened the cam marks will line up with the crank marks.

one other general thing,
when posting on this forum particularly for diagnosis of an issue, we only know what you type we are not mind readers. don't be shy with detail of the issue.
the more info you give us, the better the diagnosis will be and the less questions we will have to ask to get the diagnosis correct.

As said above the timing is dead on, thanks for the advice.

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[Davezj]

As said above the timing is dead on, thanks for the advice.

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No that is not what you typed. you never said you re did the timing and put it right.

this is why i say you need to very careful about what you type and how you word it. otherwise people will get very board, very quickly trying to help someone that will not help themselves.

Clear and full infomation is key.

[jessevr4]

No that is not what you typed. you never said you re did the timing and put it right.

this is why i say you need to very careful about what you type and how you word it. otherwise people will get very board, very quickly trying to help someone that will not help themselves.

Clear and full infomation is key.

Please read my original post where I say the timing is dead on, cheers

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[Davezj]

you might want to give full information like the post number, or use the quote feature to include the post you are talking about
the last comment you made about the cam belt timing you say you are one tooth off.

i give up good luck with sorting out.