92 240SX hesistation saga continues

[alexh]

Well,

I posted before regarding a fairly severe hesistation problem. The car is an auto and sometimes (only when it's well warmed up) there is a very noticeable hesistation when I step on the gas from a dead stop. It only happens when the car has been idling for at least 10-20 secs, like at a stop light. A few times it has been so severe that I basically had no throttle for a few seconds and I though it would stall. Car has no trouble codes.

Car runs excellent otherwise at all loads/rpms.

So, since I first started looking at this problem, I have gone through all of the diagnostic procedures listed in the manual -

Checked all vacuum hoses listed (found one burned hose from EGR control valve to EGR - no improvement).Checked vapor recovery cannisterChecked for vacuum leaks by pinching various hoses and checking for idle change.Checked plug gap and condition of plugs (ground electrode is very light but insulator is black - full tune up with new plug wires was done a few months ago)Checked timingChecked oxygen sensor with computer diagChecked TPS with ohm meter

Things I didn't check because I don't have tools etc. -

EGR valve - need something that can apply a vacuum to the EGR to open it. If this is a possibility I can get the necessary tool.

Based on my experience etc. my best bet now is the TPS. I have a tacoma truck which threw a code for bad TPS and it was very hard to verify with a ohm meter (although after several tries I could see it had dead spots). I tried running the 240 with no TPS but then of course the computer detects this and goes into limp mode so I can't compare the behaviour. Also, the problem may be intermittent as TPS problems often are. The TPS is $40 so it's not a big gamble.

The only other slightly weird thing I saw was that the air filter seemed slightly burned in the area where the hose from that valve is (forgot the name of the valve - the one that seems to let exhaust into the intake)

What do ya think?

[MaximA32]

Did this incident first present right after a good down pour?

[alexh]

Did this incident first present right after a good down pour?

No that I remember. I think it started over a year ago and it's been very slowly getting worse. '

What are you thinking?

[MaximA32]

I ran this prob;em through a diagnostic program at the dealership and it says there is a possibility of water damage to the ECM due to a leaking A-pillar. The leak is a common problem on the s13. I'd take a peak into the ECM and see what's what.

[alexh]

Holy cow,

So the cover comes off the ECM pretty easily?

[alexh]

I made a discovery on this problem but I think it's better put in a new post.

[MaximA32]

Should be just a few screws.