89 240 with a few problems...

[Prelude Guy]

I am going to do the same thing when my friend comes back into town. I am going to try his coil, MAF, and maybe his distributor to see if it fixes my hesitation issue.

Other than that, I am not sure what else to try. Maybe a compression check.

[Pa240drifter]

Update(again). Bought a new MAF, put it in. Acts the same. I changed my fan clutch cause it was making noise and was broken, now I can hear the engine better. I also noticed a vac hose off the FPR, put it back on. I noticed that if I hold the gas at lower rpms, the motor knocks.... badly. If I press the accelerator a little harder it goes away until about 2500-3000rpms. I noticed this before the MAF swap, and still after. Going to check the timing tonight, but other than that, how screwed am I? If the motor is shot, I'm not sure I'll be able to afford a new one. I'm beginning to think this has to do with a vac problem, since I've found numerous rotted hoses. Help is appreciated, thanks

[s13sr20chris]

low knock or high knock? if it sounds wierd like marbles in a can but not steady and rythmic it is prob spark knock(ping). that is bad but may not be mechanical. if it is deep or high but fairly rythmic it is prob mechanical.

[Pa240drifter]

It sounds like spark knock to me. I retarded the timing and the car runs like crap, but the knock is gone. I drove it like this for a bit, but the idle got real unstable and horrible. There is now a hesitation at about 2250-3000rpms and I've got NO power. I decided to go get some high grade gas(93 octane) and put it in. The knock is nearly gone. It only happens occasionally. This is gonna be annoying to fix.

[navysnail]

what is the timing at right now then?

[s13sr20chris]

crud, that does sound like spark knock. if your timing is right, it could be fuel. could also be something like combustion chamber deposits or damage. i had an issue on my old honda like that. never was able to resolve it. had to run premium gas at stock timing and it would still happen occasionally. i tried everything short of engine overhaul.

[Pa240drifter]

well, time to bring this back to life(again) my MAF change did nothing at all. im beginning to think i have a vac leak somewhere. i bought a air/fuel ratio meter and i noticed some odd things. at idle my a/f ratio is rich. it also switches to full rich mode fairly early in the throttle. im beginning to wonder if maybe my tps is shot, it has been 14 years and 137k miles. i also found a ripped section in my intake hose, fixed it, no luck. need more stuff to try.

[Pa240drifter]

ok, back again. this time i noticed i couldnt go above 4700 rpms, then the car bogged like it had no spark or something, and the revs had to go to about 4k before it would go again. traced it back to a clogged cat(so i think). knocked out the cat and now it revs right, but still dies at 5200.

[s13sr20chris]

i realize i forgot to mention the 5th gear sensor. it will cause a revlimiter at 5000rpm in all gears instead of just fifth.

[jsr240sx]

i have read all postings however you didnt mention if you have your check engine light on, if so i have the same problem, i have replaced my engine twice but with the same ecu, my check engine light is still on and my understanding is the if the light is on the engine runs on safe mode. My car hits its limit around 5000-5500 rmp and and it throws back. I have a 89240sx fast back. stock.

[Pa240drifter]

my car is not equipped with a check engine light on the dash, and i havent pulled the ecu cover to check.