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My Z

630 Views 13 Replies 10 Participants Last post by  Mr-Always
Hey guys it's been a while. I got under the Z for the first time in almost a year. She's been collecting dust and cob webbs...and I've been pretty much AWOL from the Z community also. Part of that is because the problems I've been having with her shortly after the engine re-build. Well, I sat in my car and I got that feeling again...kind of like my Z is telling me to fix me! lol...I guess that sounds corny but putting my hands on the steering wheel brought back a lot of memories. Now I've got the energy and drive to work on my baby again and my first step was to follow your advice and replace the fuel pump for the problem I was having with her. I got a great deal on a Vortex T-rex fuel pump and bolted it right in. Everything started up just fine after I checked the fluids but the stumbling problem is still there. Once warmed up, I can gas the car in neutral to build some boost but it would burp and gurgle as if the car is starving for fuel while it struggled to build some RPM's. While the car is moving under load I can get about 3psi before there's a major loss in power which would normally force me to let off. Also the air/fuel meter is reading to the faaar left (lean) at speed while boosting and while revving the motor at idle. So so far, I've replaced the fuel filter and replaced the fuel pump. What's the next thing that I should check? I've been told a lot of things like the fuel injectors are clogged to the O2 censor is bad or that the Air Flow Meter is the problem...I honestly do not know where to start next. I'm guessing the fuel injectors but hoping to get some educated advice from you guys. I'm so feening for that power again and just want to do what ever it takes to get her back on the road.

Post Edited (Oct 17, 7:50pm)
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What computer is running the engine? Turbo ECU or aftermarket?
Save your money up for a stand alone EFI system rather that throwing good money after bad on what's there..
" While the car is moving under load I can get about 3psi",

Question why does the car have to be moving to build boost?

How in the heck does it know if its moving?

Always wondered that

Sorry had to ask, probably a real easy answer to this .

I'm currently running the stock ecu which never gave me a problem by the way and I was able to run 15-16psi prior to the engine swap/rebuild....so why would it give me a problem now other than the fact that it could be faulty? Besides, I should be able to get at least the stock boost pressure of 6-7psi but I can't even get that now. I've tried cleaning the contacts to the ECU by the way and I've also cleaned the contacts to pretty much all the sensors under the hood. Can't be a vacuum leak because other than my boost gauge, I've gotten rid of all the vaccum lines under the hood and I'm running the shaved intake manifold. All my intercooler pipes are sealed and I'm using heavy duty T-bolt clamps to hold them down. As for a stand alone engine management, I've got my eye on the Megasquirt kit but I'm saving that for the future. I know I can have a decent set up with what I have now and maybe some SVO injectors and RRFPR might do the trick. I just need to figure out what the heck is going on so the car can be driveable again....

as for the load question, I don't have a scientific answer for that one lol but when I say "under load" I'm talking about when the car is in gear and it's moving forward at WOT.

thanks for any help!

Post Edited (Oct 18, 4:58am)
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I believe the wastegate stayes open whenever the car is in neutral.
Steves280, what is a stand alone EFI? Sorry for the ignorance but sounds like a good idea. Also having problem with my existing EFI set up.

Stand alone is a programable ECU.It gives you the ability to richen/leanout your efi system at any rpm range.You can also advance/retard timing.Some of the more expensive systems can control boost,be used as a security system(a code needs to be input befoer ignition will operate) and be a turbo timer to allow proper cooldown.Prices between $300-$2k.
I was guessing turbo lag kept the psi down. The turbo can't spool fast enough to create boost for the engine. The engine is reving up fast than the turbo can. Well that's my understanding.

Ratedz- what all was changed durning the engine swap? Injectors, fpr? Is the fpr hooked up to the manifold? or are turbos different from the n/a's in that respect.
Hi guys, goldfish, the car ran for a total of two months after the swap. In that time, I put about 500-600 miles for the break in and the car ran flawlessly. Boosted to about 15-16 psi but I did start to feel a little of the hesitation but wasn't too bad at the time. Then I parked it for about six months. Got it back on the road but only lasted for two weeks as the problem got worse and was told here to replace the fule pump. Then it sat for another three months or so until I started it yesterday after the fuel pump replacement. The fuel pressure regulator is on the fuel rail. The injectors where carried over from my old engine with the exception of two. I replaced them with two out of the set that came with the rebuilt motor. As for the installation of the motor, I know everything was working just right until this problem started towards the 600mile of the break in process. I'm still scratching my head as I'm not really sure which part of the car to tackle next...

Is this the same problems from your last posts?


Then I don't know what to say, other than put in clean plugs, run then pull plugs to see how they read. I think we just past my experince, sorry.
Yes Sir! That is it...only now my car is barely driveable ;(

I just got back from tinkering with the Z and I did find that the hose to the bottom of the throttle body was broken at the nipple with the other part of the hose no where to be found. It's been a while so I can't remember exactly where it goes...can anyone refresh my memory? after closer inspection, the hose was pretty dry rotted which would explain it breaking off like it did. Now, this is probably an obvious question but would that have an effect on the way it's running right now? the hole is not that big but I suppose a vaccuum leak is a vaccuum leak. Anyway, I'll have to wait to re-start her as my loaner battery is gone...I'll plug it up and see how it idles ect hopefully sometime this week.

Please feel free to chime in on this as it might be more than just the vacuum leak....I hope not....
Could very well be gunked up or faulty injectors. Check them by holding the tip of a screw driver to each injector and put your ear to the handle. You should hear each one ticking if they are working. If they sound like they are all working, then try putting a half a can of Sea Foam into the gas tank with a full tank of gas and drive it immediately on the highway for a while. This will clean out any sh!t in the fuel system. My 280Z had a little hesitation a while back ago and I did what I mentioned above and she ran and took off at stop lights like a dream.

Good luck ratedZ. Good to hear from you again.

If it idles fine, but runs like crap when you accelerate, then it is a fuel problem.
Problem is most definately sludge/rust/dirt in the tank, crap in the lines, etc.
Since you ran it, you should check the screen in the pump(if that pump has one). Sending unit could also be clogged. Drop the tank, clean it with paint thinner, and alcohol.
Or go with the por 15 tank cleaning/sealing kit(recommended).
Blow everything(lines, tubes) out with an air compressor.

Your spark plugs may fouled, also. Check them first.
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