I have no idea! Boost problem.

[Z32man]

today i drove my z and it was driving fine with little idle problems. so i adjusted my TPS a little to see if that would help a little. it helped enough for me to drive to the store but when i drove home i accelerated and when i start getting boost, my car would not accelerate. as i let off the gas pedal it would start to accelerate better than when i pushed down the pedal. would this have to do with my adjustment of the TPS or is it something completely different?

[Z32man]

also when i turned it off then back on, it ran normally.

[worldisgrand]

That's funny, I am having similar problems with my car right now except I can get it up to about 3lbs before it starts to do the same thing. I can rev it up all day in neutral and no problems. But if it gets under load it bogs down until it reaches atmosphere pressure again. I checked my turbo's, both are good, good compression, getting fuel, good maf, good throttle positioning sensor, all cylinders firing, good injectors, good fuel pressure regulator and dampener, code 55. It has to be something simple since I just got done rebuilding everything.

[300ZXttZMAN]

Boost Leak, Boost Leak, Boost Leak, Boost Leak, Boost Leak, Boost Leak, Boost Leak, Boost Leak, Boost Leak, Boost Leak, Boost Leak, Boost Leak, Boost Leak, Boost Leak, Boost Leak, Boost Leak.

This is why I started my entire build I thought my motor was done. My car wouldn't rev past 3k in all forward gears. And wouldn't build more than 3 pounds of boost. Come to find out I had a quarter sized hole in my RH intercooler endtank.

If your car won't let you rev her up freely this is what I say you check for a boost BOOST LEAK!

Remember that the Z32 has 23 feet of intercooler piping so finding a boost leak could be tricky!

[worldisgrand]

I was afraid that's what it was, just needed someone to slap me in the face with it. Thanks 300zxttzman . I am trying to pin point exactly where its coming from and having no success. I'm not hearing any from the intercooler piping. I am hearing it from the backside of the motor.

I am thinking about putting the back end up on jackstands with a jack under the diff and letting the car build boost in drive and then spraying soapy water.

Its the only thing left and its driving me up the wall . How about you z32man, any luck so far? I too agree with 300zxttzman on this, the boost leak I have can't be very big, so almost anything could be the problem. The next thing I am going to do is pull the upper plenum off and check all the seals around the fuel rail to the lower plenum and move up from there.

[Z32man]

but the thing is when it happens to me, i get full boost. it will rev up in gear but very very slowly. and it doesnt happen every time i drive. usually if i just restart my car it fixes the problem. is it still a boost leak?

[Z32man]

Scratch that, it doesn't accelerate at all.

[Z32man]

also when it starts happening, and i rev it up, it will backfire.

[worldisgrand]

Are you getting any codes?

[NolimitZ32]

Rev up and backfire is a sign of vacuum leak.

[worldisgrand]

Boost Leak, Boost Leak, Boost Leak, Boost Leak, Boost Leak, Boost Leak, Boost Leak, Boost Leak, Boost Leak, Boost Leak, Boost Leak, Boost Leak, Boost Leak, Boost Leak, Boost Leak, Boost Leak.

I ended up finding out that I needed to go a little tighter on the nuts and bolts on the lower intake plenum. I actually had them in spec with ft lbs and then had to take it off to get to the detonation sensor and when I did I got distracted with another issue at the time and didn't tighten them up tight enough. Now no problem! SOMEONE PLEASE SLAP ME FOR THIS!!!!

If any advice I can give to anyone is to do it right the first time.

[NolimitZ32]

Present your cheek. . . .

[Z32man]

Will a leaking fuel rail seal cause a boost leak?

[Z32man]

Will a leaking fuel rail seal cause a boost leak?

BUMP!

[Z32man]

Ok so i have still not found out the problem. Let me rephrase it. In the mornings on cold starts, it starts fine then after a second the rpms get very low. When i push the gas, it doesnt do anything. I have to pump the gas multiple times to get the RPMs up and then i have to hold it down a little so it will stay at a high enough RPM so the car will warm up. Once it warms up though, the car runs just fine. When i drive it normal, it runs fine as well. If I floor it in first then go into second then third, it boosts and runs fine. The problems start to happen when i am boosting at lower RPMs, such as if i go up a hill without downshifting of if im on the highway in 5th gear and try to floor it. The problem i am getting is when this happens, the car feels as if it is bogging down and it will not accelerate at all until i restart the car. Once I restart the car, it runs just fine again until i boost in low RPMs. Someone please help! I tried to go to the dealership and get a boost leak test but they said the wouldnt be able to do it.

[Z32man]

BUMP! I need this fixed ASAP.

[mrmoose]

how did you adjust your tps? it has to be set at .45-.5v you cant just move it to where it sounds like it runs good. could be a boost leak, easy way to tell is to use a can of brake or starter fluid and spray around the suspected areas of leakage. BE CAREFUL and spray only a few shots at a time, dont need any lost eye brows or worse, stuff is highly flammable. if you hear the idle jump higher then you have found your leak.

[Z32man]

ok i will adjust my TPS to .45-.5 volts tomorrow morning. if that doesnt change anything i will let you know. I dont have enough time to get a boost leak tester so i am getting it tested at a performance shop. hopefully this will fix my problems.

[Z32man]

Ok, so i adjusted my TPS to the specs. It started to run better, but the idle is worse. Sometimes it idles perfectly at 7k rpms but other times if im at a stop light, the idle will get very low and bouce at 5k rpms and it sounds like it may stall. I havnt allowed it to stall. Also if i really get on it, at around 4k rpms, i hear a weird sound from the exhaust, almost as if its misfiring. It shouldnt be misfiring because i replaced my injectors with all new style injectors about a year ago.

[t.mcginley.jr]

I'm going to assume that by 7k rpms at idle you mean 700 rpms and by 5k you mean 500 rpms when the idle starts bouncing. Usually a bouncy idle means the TPS is shot. Have you tried replacing it yet instead of just setting it to specs? And did you get the boost leak check done yet?

[Z32man]

Oh ya on the first 7k and 5k I meant 700 and 500. No I have not tried a new one. For the boost leak test, should I go somewhere and get it done or should I buy the boost leak tester from z1motoraports and do it myself?

[t.mcginley.jr]

I'm thinking you might as well order the one from Z1. It's only $24 (with the pressure gauge) + shipping. Any shop will probably charge you more than that unless you're friends with them. That way you can do it as many times as you want and you will have it for future tests

[Z32man]

I ordered the boost leak tester and when i add air, the gauge does not even go up at all. I tried putting air in it for about 2 minutes and the gauge didnt move at all. When i drive it, it doesnt seem like the boost leak is that big. Maybe im doing it wrong? i need some help.

[nissanfreak12]

Put the engine at TDC, then give it a shot. if it still doesn't hold, you have a leak.

[Z32man]

i have no idea how to put it at top dead center.

[nissanfreak12]

Turn the crank pulley till the mark on the pulley matches 0 on the cover. Or take the #1 spark plug out and when the piston is at its highest point, that is TDC. Easiest is turning the engine until mark and 0 match on the crank pulley.

[Z32man]

Also i failed to say that if i unplug my tps (the gray connector) the idle is fine but it still does the previous problem above when it bogs down and i cant accelerate until i restart the car. Should i just go ahead and get a new tps or should i figure out the boost leak situation first?

[t.mcginley.jr]

You take off the front airbox/cone filter whatever you've got and the MAF, stick the boost leak tester in there and add air. If the gauge doesn't move at all then either you have a big leak somewhere, the gauge is faulty, or your air compressor is toast. You probably have both a boost leak and a bad tps so just get the tps and try and find the leak. Did you try and inspect all the piping yet?

[Z32man]

I pulled my plenum and inspected all of the piping that i could see. Everything seems to be good. I also replaced my TPS and it seems to be running better but still every once in awhile the idle gets lows when im stopped at a stop light. That bogging down problems has happened but not as often as before. Is there any other sensor that could be causing this problem? I will be doing the boost leak test again as soon as i have time.

[t.mcginley.jr]

A bad MAF itself can cause the issue, or a miscalibrated TPS. Did you check your intercoolers themselves for any leaks/holes? And make sure all the clamps are tight? Bad PCV valves can also give you some issues like this.