project 92z Posted September 19, 2016 Report Share Posted September 19, 2016 I recently purchased a 2nd Z34. This one a 92. The guy had some plans early on but a 24 year old car is not a good car for a 24 year old struggling young man so after seeing mine and wanting it to go to a "good" home, he sold it to me cheap. Or at least that was the lie he told me. Anyway what i thought was a simple brake job and vacuum leak had taken on a whole new life. Anyone see the movie Money Pit[emoji33]. So far nothing terminal but a lot more than i thought. What i need help with so far is what i thought was a vacuum leak. On start up the engines idle it's about 2200 rpm instead of the 900 or so I'm used to. It will level out a bit after it goes into gear. I've found and fixed the vac leaks, replaced the IAC and egr. The timing belt needs to be replaced but not sure if that would do anything to cold curb idle speed. Any other ideas out there? Sent from my LGLS775 using Tapatalk Quote Link to comment Share on other sites More sharing options...
Psych0matt Posted September 19, 2016 Report Share Posted September 19, 2016 It is a vacuum leak. Intake gaskets. Very common. Luckily it's not too bad of a job, just a little tedious. Quote Link to comment Share on other sites More sharing options...
Nas Escobar Posted September 19, 2016 Report Share Posted September 19, 2016 I recently purchased a 2nd Z34. This one a 92. The guy had some plans early on but a 24 year old car is not a good car for a 24 year old struggling young man so after seeing mine and wanting it to go to a "good" home, he sold it to me cheap. Or at least that was the lie he told me. Anyway what i thought was a simple brake job and vacuum leak had taken on a whole new life. Anyone see the movie Money Pit[emoji33]. So far nothing terminal but a lot more than i thought. What i need help with so far is what i thought was a vacuum leak. On start up the engines idle it's about 2200 rpm instead of the 900 or so I'm used to. It will level out a bit after it goes into gear. I've found and fixed the vac leaks, replaced the IAC and egr. The timing belt needs to be replaced but not sure if that would do anything to cold curb idle speed. Any other ideas out there? Sent from my LGLS775 using Tapatalk I wouldn't be concerned about the car becoming a money pit. Worse comes to worst, you're simply gonna have to replace the ECM. I went through that with my 93. Anyways, if you let the car idle out of gear, does it go down or go up to the rev limiter? In gear, does it surge? What's your RPM level on gear? Also, make sure the vacuum lines are routed correctly. The previous owner of mine had hooked up the washer line to the vacuum lines and the vacuum ball was not connected which caused a lot of issues with the HVAC and cruise not working. Quote Link to comment Share on other sites More sharing options...
Imp558 Posted September 19, 2016 Report Share Posted September 19, 2016 In theory if you unplug the iac and it's still idling high it has to be air entering in somewhere still. Quote Link to comment Share on other sites More sharing options...
project 92z Posted September 19, 2016 Author Report Share Posted September 19, 2016 Thanks. I did replace the plenum gasket but stopped there (leaking fuel from the injectors). Prob should've gone all the way with the ui gaskets set. Wouldn't have hurt. Also I'm pretty sure about the routing and integrity of the vac lines now. When i put it in gear it doesn't surge at all. Just a clunk since the rpms are so hi but they come down then. I'll try unplugging the iac later and repost. Sent from my LGLS775 using Tapatalk Quote Link to comment Share on other sites More sharing options...
Galaxie500XL Posted September 19, 2016 Report Share Posted September 19, 2016 A bad throttle position sensor can do that, too, but the only way you're going to know that for sure is with a scantool that will let you see engine data. It could be the gaskets, went through that twice with mine..but I later had a TPS issue that matched your symptoms. Do you have coolant pooling under the manifold? If so, the gaskets are definitely bad. Quote Link to comment Share on other sites More sharing options...
Padgett Posted September 19, 2016 Report Share Posted September 19, 2016 Mine does that too. Have the gaskets just waiting for cooler weather. Is running 1500-1800 on a command for about 1k. Fine once warmed up. Quote Link to comment Share on other sites More sharing options...
White93z34 Posted September 19, 2016 Report Share Posted September 19, 2016 Sounds like lower intake gaskets. Could also be a split brake booster hose, though if you did the plenum gasket I'd imagine you'd have seen it. Quote Link to comment Share on other sites More sharing options...
Nas Escobar Posted September 20, 2016 Report Share Posted September 20, 2016 Thanks. I did replace the plenum gasket but stopped there (leaking fuel from the injectors). Prob should've gone all the way with the ui gaskets set. Wouldn't have hurt. Also I'm pretty sure about the routing and integrity of the vac lines now. When i put it in gear it doesn't surge at all. Just a clunk since the rpms are so hi but they come down then. I'll try unplugging the iac later and repost. Sent from my LGLS775 using Tapatalk Define "leaking fuel from the injectors". The fuel should leak from the fuel rail when disconnected, but not from the injectors themselves when removed, especially if it's on the side where it goes into the manifold. Quote Link to comment Share on other sites More sharing options...
project 92z Posted September 21, 2016 Author Report Share Posted September 21, 2016 The injector issues were definitely the o-rings. Half go them were noticeably damaged. Looks like they had placed them in the manifold them tried to force the rail down on top all with no lube. There's a lot of half ass wanna- be mechanic problems I've found. That's why i said i should've done the lower intake gaskets too. Sent from my LGLS775 using Tapatalk Nas Escobar 1 Quote Link to comment Share on other sites More sharing options...
project 92z Posted September 21, 2016 Author Report Share Posted September 21, 2016 The injector issues were definitely the o-rings. Half go them were noticeably damaged. Looks like they had placed them in the manifold them tried to force the rail down on top all with no lube. There's a lot of half ass wanna- be mechanic problems I've found. That's why i said i should've done the upper and lower intake gaskets too. Sent from my LGLS775 using Tapatalk Sent from my LGLS775 using Tapatalk Quote Link to comment Share on other sites More sharing options...
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