Still tracking down a hesitation problem, and now I'm running out of things to check. So far I've checked off plugs, connection corrosion, timing, tps, coolant temp sensor, vacuum leaks, fuel pressure, injectors, fuel quality, fuel filter, air filter,and o2 sensors.
The problem is the car will "bog" down really bad after a few seconds of idle time or after highway coasting. Afterwards it runs fine and has power throughout. It's consistent aside from when its at high idle. I've captured video of both its showing a code 55 and the hesitation seen from my tach.
also noticed this engine seems to be pulling close to 30 inHg. Not sure if this makes any difference just noticed it seems a like high compared to others.
http://s55.photobucket.com/user/MunionC ... 7.mp4.html
http://s55.photobucket.com/user/MunionC ... 6.mp4.html
help with hesitation
Re: help with hesitation
My car was a budget z too, worth about 2 nickels. LOL.
Maybe I can help. I had a similar hesitation problem, actually almost to the letter. The only difference is that I wasn't throwing a code.
There are about 30 some odd reasons that can cause hesitations. For me I replaced the following and each time it got better.
I initially replaced the fuel pump, then the maf sensor, replaced all vacuum hoses and fixed all leaks. Check the short PTU harness. Mine looked normal but upon replacing it with a new one I had an immediate improvement.
Also check the fuel relay itself and the fuel pump control unit. The FPCU controls the voltage to the fuel pump. it is monitored by the ECU and so naturally when you're idling it sends a lower voltage (5v...i think) and when you step on it at higher speeds it supplies 12v. The FPCU can fail and in my case it would not provide enough juice at idle or low rpms and when the needle moved higher into the 2-3k the car would respond like a brand new race car. For me my hesitation was fixed (at least for now) by sheer luck. Due to some a-hole driver I had to really step on mine and in doing so I redlined into about 6200 rpms, after which my FPCU either got stuck on high and will likely take a dump altogether or the higher jolt fixed it. no more hesitation or lag. lol. Whether it is a permanent fix has yet to be determined, but if it starts again the FPCU will be my first stop.
Hope it helps. Good luck
Maybe I can help. I had a similar hesitation problem, actually almost to the letter. The only difference is that I wasn't throwing a code.
There are about 30 some odd reasons that can cause hesitations. For me I replaced the following and each time it got better.
I initially replaced the fuel pump, then the maf sensor, replaced all vacuum hoses and fixed all leaks. Check the short PTU harness. Mine looked normal but upon replacing it with a new one I had an immediate improvement.
Also check the fuel relay itself and the fuel pump control unit. The FPCU controls the voltage to the fuel pump. it is monitored by the ECU and so naturally when you're idling it sends a lower voltage (5v...i think) and when you step on it at higher speeds it supplies 12v. The FPCU can fail and in my case it would not provide enough juice at idle or low rpms and when the needle moved higher into the 2-3k the car would respond like a brand new race car. For me my hesitation was fixed (at least for now) by sheer luck. Due to some a-hole driver I had to really step on mine and in doing so I redlined into about 6200 rpms, after which my FPCU either got stuck on high and will likely take a dump altogether or the higher jolt fixed it. no more hesitation or lag. lol. Whether it is a permanent fix has yet to be determined, but if it starts again the FPCU will be my first stop.
Hope it helps. Good luck
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budget300zx
- Posts: 199
- Joined: Thu May 29, 2014 9:11 pm
- Car: 90 300zx NA
Re: help with hesitation
checked that as well the fuel pressure stays steady leaning towards a sticking iac valve. messed with the hoses and it seems to have went away for now.