Learn me turbo troubleshooting.

Occasionally when i'm driving this Skyline boost will cut in and out on initial acceleration, usually at 3rd gear and higher, then it will stop. When it has been running for a while or run hard this never happens. For example last night I went to autocross and it was fine, however on the way there on highway entry less than 10 minutes into my commute to there it did this. The only "cure" is to stay out of boost for a bit then it runs fine.

Since it doesn't happen at WOT when there is the most air flow after it's been running a while I don't think it would be vacuum lines or the intercooler piping it's probably cutting fuel. So I'm wondering what is causing this. MAF sensor?

Can you pull the codes from the computer? Also, make sure the waste gate is working properly, has the vacuum lines OK on it and make sure the vacuum switch to the waste gate is OK, assuming it has one.

I'll check that all out. At work right now.

Is the boost cutting, or it it fuel cut? Are you running more boost then stock? I know nothing about the engine management on a Skyline, but lots of turbo cars cut fuel when the detect an overboost event. Many don't actually sense boost, but they look for a high reading from the airflow sensor. If your car is borderline, it may fuel cut when you first start driving, when the engine bay is cold. Once it warms up, the hotter, less dense air no longer shows up as a high reading at the airflow sensor. Also check for boost leaks, since they will cause the turbo to pull more air through the air flow sensor then the engine is really using.

Might be in safety boost (should show a code. Could be detecting knock. Doesn't sound like a MAF problem. The RB25DET ecu is very similar to the Z32. Your 89? should have the RB20DET? Which might be more similar to the electronic found on the Z31.

I'd follow Dr Hess's suggestion and look for a vacuum leak. When the motor is cold the hoses will contract and potentially open up any cracks or loose connections. Then, once hot, the hoses will swell and seal themselves due the expansion from the heat.

I'm sure that cleverer wrenches that I will suggest a way to track vacuum leaks. At this time my only way to do it is by ear. Listen for a whistling noise...

Will have time to look at this later this week, thanks for the suggestions.

There is no check engine light or anything like that which would usually show up if there was a fault code. IDK how this car works but i'd assume a light would come up if that was happening.

Fun fact, from my experience the Nissan CEL does not always illuminate when you have a fault code, YMMV.

You are correct as it did not. I found what the issue was, fuel pump was having issues. I had a Nismo unit I got for free I was going to put in sometime in the future. Put that in and this hasn't happened since.