Surging need help!

[Shinxxy]

If you haven't changed your cap and rotor in a while, there's your motivation to do it. Old cap and cracked rotor could be your problem, seems extreme for a rotor but if it isn't riding correctly at higher rpm then there you go.

An update on my surge: On a whim I replaced my O2 sensor since I had a new one laying around. Seems that I am beating it down bit by bit, the hesitation is less noticeable and now only happens in a small RPM range. New rotor, cap, wires, plugs, valve adjustment, TPS and now O2 sensor. I am going to go after my AFM next...all just to find a vacuum leak somewhere that I can't pin down I bet.

The only thing I don't understand is when I put the ECU in from a 94 4runner, it revs up to 3000rpm. Then eventually when it warms up it won't let me go over 1800-2000rpm. There's a good chance that this crack in the rotor could be it. yeah?

 

[turboSR5]

Hard to say if that is your entire problem, any crack on anything in or on your distributor is good reason to replace it asap. I'm curious as to what your cap looks like, it may be very old, worn and dirty. If it is extreme, then at higher RPM you could be having trouble getting spark past it due to resistance as things progressively get warmer. That rotor might have too much play in it due to the crack or it could be worn slap out.

I have no idea why the newer ECU can push you to higher RPMs. The only thing I can come up with is maybe that ECU has slightly different fuel/ignition maps so the problem just moves to a different RPM load. I don't know if newer models had different electronics that required new mapping or if they just "upgraded" the maps as they went along. If I were you I would stick with the ECU for your year as long as it isn't toast.

 

[fishrod]

Yeah first thing that was changed when I first got the car was the plugs/wires/rotor and it didnt make any difference at all.

At one point I was convinced it was the EGR valve but I didnt have the time/money/skills to replace it. Then it became summer and the problem went away and I forgot about it.

 

[Shinxxy]

Today I replaced the distributor cap and rotor. Well, that didn't work.. BUT I did disconnect the TPS, and it worked! No more bogging at 2000rpm. Now could it just be the sensor, and could it be driven with it disconnected?

 

[turboSR5]

LOL, I didn't want to keep pounding on you about your TPS, but it looks like you finally got around to messing with it. You should just replace it, some people have success with removing them and cleaning the gunk out until the spring can return. I bought mine for my 87 RE for around $80, I think the one you want is about $10 or so higher.

If you haven't cleaned your TB yet I would say remove it, take off your old TPS and clean the TB very well with carb cleaner, blow out the vacuum ports. Install and adjust new TPS and finally reinstall your TB. It is much easier to adjust your TPS with the TB off of the intake. Another good tip is to replace the stock screws with allen head bolts in case you need to adjust it later on with TB attached.

 

[Shinxxy]

LOL, I didn't want to keep pounding on you about your TPS, but it looks like you finally got around to messing with it. You should just replace it, some people have success with removing them and cleaning the gunk out until the spring can return. I bought mine for my 87 RE for around $80, I think the one you want is about $10 or so higher.

If you haven't cleaned your TB yet I would say remove it, take off your old TPS and clean the TB very well with carb cleaner, blow out the vacuum ports. Install and adjust new TPS and finally reinstall your TB. It is much easier to adjust your TPS with the TB off of the intake. Another good tip is to replace the stock screws with allen head bolts in case you need to adjust it later on with TB attached.

Hey thanks for the tip. You helped me out a lot on this one I Appreciate it. Did you get to your AFM yet?

 

[turboSR5]

Hey thanks for the tip. You helped me out a lot on this one I Appreciate it. Did you get to your AFM yet?

Glad I could give you some usefull ideas. I have my problem all squared away now. I noticed my idle started creeping lower the last couple of days so I reset it to 750 then rechecked my timing. My timing was way off and once timed and tuned right no more hesistation anywhere.