Idleing rough and sometimes not at all please help

[NewGen]

Ok I have a 1988 toyota supra 7mgte I just put a Titan Motor Sports 1.4mm MHG on it. The car use to have idleing issues before it warmed up. Once it reached operating temp it would idle just fine. Now it idles very rough once it hits operating temp and not at all when its cool. It usually tries to idle around 400 rpm which I know is low. The first test I tried was removing the pcv from the throttle body. The car would stay runing but only if you held your foot on the gas. Should it die all together? If it should die altogether that means I have an outside air source entering my intake somewhere correct? Does Anyone have any other suggestions on what I should try replacing first or maybe other tests I could perform. I have been using the search function to try to help myself but I havnt found anything thats worked yet.

Side Note: I had to reuse my old upper intake gasket because I fubar the stock one and I havnt had the funds to replace it yet. I just got paid today so I will order one once I leave work.

thanks for your help

matt

 

[Jaguar_5]

Here's a hint:

I strongly feel that we should have a rule here, that will ensure that before anyone makes any tech-help threads, they need to check the ECU for codes FIRST before doing anything else, so that we at least have some diagnosis to work with

 

[NewGen]

Here's a hint:

I strongly feel that we should have a rule here, that will ensure that before anyone makes any tech-help threads, they need to check the ECU for codes FIRST before doing anything else, so that we at least have some diagnosis to work with

theres arnt any codes. I will remember to post that next time I have a problem.

 

[ATL88Supra]

when you had the motor out did you clean the icv? check for vac leaks etc

also for shits a giggles do a compression check.

 

[NewGen]

I didnt pull the motor. We just took the head off and I didnt clean it but I will when I get home. I will also do a compression check after I retorque my head. No vac leaks that i could tell most of the lines are brand new. But I do think it might be leaking from the upper intake manifold gasket.

 

[IwantMKIII]

boost leak test will give any leaks. Its possible your injector insulators are bad or not seated correctly.

 

[NewGen]

I didnt have to remove the fuel rail when I milled the head. The guy before me had the injectors cleaned and calibrated and the car idled the first 4 months I owned it. The car first started having problems idleing when my turbo seals started to go out but I replaced it 3 months ago with a 57 trim

 

[IwantMKIII]

^doesn't matter. just b/c something worked last week doesn't mean it will work this week

 

[NewGen]

K, What tests can I be doing to check and see if this is the problem. I will perform a boost leak test also. I've gota funny feeling I might be leaking out my stock BOV at vacuum.

 

[IwantMKIII]

^boost leak will let you know of any leaks. DO NOT PLUG PCV SYSTEM DURING TEST.

FYI, stock setup does not utilize a BOV

 

[NewGen]

^boost leak will let you know of any leaks. DO NOT PLUG PCV SYSTEM DURING TEST.

FYI, stock setup does not utilize a BOV

what kind of valve is it considered? Its some kind of presure release valve. I've done boost leak tests before. How do I check to see if the injector insulation is bad?

 

[gaboonviper85]

I'd also recomend hoseing down your intake with carb cleaner to see if you have a vac leak considering you used the old gasket....a vac leak will cause the issues you describe...

And milling a head without removeing the injectors is crazy...that's a dirty process with really fine aluminum chips that could foul an injector....

 

[gaboonviper85]

You will hear air escape past the rubber bushings around the injectors....

 

[NewGen]

I'd also recomend hoseing down your intake with carb cleaner to see if you have a vac leak considering you used the old gasket....a vac leak will cause the issues you describe...

And milling a head without removeing the injectors is crazy...that's a dirty process with really fine aluminum chips that could foul an injector....

I wasnt aware of that and the machine shop I took it to didnt think it was a big deal. I will have a new gasket on it by tomarrow night but I will go ahead and check it anyways. Also the car runs fine at wide open throttle. If I fouled an injector wouldnt it miss at wot?

 

[gaboonviper85]

I wasnt aware of that and the machine shop I took it to didnt think it was a big deal. I will have a new gasket on it by tomarrow night but I will go ahead and check it anyways.

I'm a machinist and I would never do such a thing!!!

 

[NewGen]

K back to my other question if it was fouled wouldnt it miss at WOT?

 

[gaboonviper85]

Maybe...maybe not......things don't always break the same....odds are your injectors are fine but it was still not smart.

 

[NewGen]

Maybe...maybe not......things don't always break the same....odds are your injectors are fine but it was still not smart.

K Thanks for the advice. I will remember to take it off next time

 

[IwantMKIII]

I'd also recomend hoseing down your intake with carb cleaner to see if you have a vac leak considering you used the old gasket....a vac leak will cause the issues you describe...

And milling a head without removeing the injectors is crazy...that's a dirty process with really fine aluminum chips that could foul an injector....

scratch this idea, its useless as a boost leak check will already find your leaks in the vac system.

As far as the injectors are concerned, they should be fine. Any fine particles would just be ejected at the first opening of the injector anyway.

 

[jdub]

It's likely a pirate air problem. Make sure the TB plate fully is fully closed, then block off the ISCV and the PCV at the respective openings. The engine should die...if it doesn't, you have a vac leak somewhere...this is generally indicative of a high idle though.

For a low idle, check the ISCV for proper operation per the TSRM. You might want to remove and clean it. The check valve under it may be clogged or stuck closed, if so, it will need to be replaced.