Rich spikes cause stumble at cruise

Then use the relay from your A/C condensor fan. It's located on the passenger's side strut tower.

Did you verify the ECT resistances and voltages at cold, warm, and hot ranges? My experience with LH24 is Rich during cruise is almost always ECT or O2 sensor issues.

haha. well...what I thought was the RSR was the a.c. condenser relay. the one hanging on the coolant reservoir? I stopped by my brothers, swapped relays with the one on the driver side strut tower and the car was a crank, no start. I figured it was the ****ty harness that's attatched to the so called "RSR", tried wiggling, no dice. my bro walks over and says I'm pretty sure the driver side one is the RSR, swapped relays back to the original places, and the car starts no problem.

the driver side harness is actually not terrible. not like the one on the coolant tank. relay looks fine, but im very hesitant on chopping up a good looking harness in hopes it'll fix things... I guess ill wait for the new one in the next dew days?

I have checked resistances from the ECT while warm(sitting for about 3 hours in 80 degree temps) and while cold (sitting over night) it checks out. havent checked voltages tho.

I took a video on the way home tonight of me cruising, it stumbling, then some in boost, then it stumbling some more...ill post it later after it uploads...

https://youtu.be/2snuOZSHO0o

cruising, then ~10 psi and it richens up, I let off and it leans out, go back to cruising and it stumbles more..

Uncleknucklez said:

Did you verify the ECT resistances and voltages at cold, warm, and hot ranges? My experience with LH24 is Rich during cruise is almost always ECT or O2 sensor issues.

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o2, I havent checked yet. but everything ive read says the o2 doesnt affect anything in "closed loop" like while cruising. right? or have I got it backwards?

Mbeas96 said:

o2, I havent checked yet. but everything ive read says the o2 doesnt affect anything in "closed loop" like while cruising. right? or have I got it backwards?

Click to expand...

It's in the name, closed loop indicates it's getting feedback from the 02 sensor and adjusting the mixture, open loop runs off a preset table.

ah...I do have it backwards. well, the RSR came in the mail yesterday. ill pop that in and reassess the harness.

then checking voltage at the o2 soinds like my next step

so, the RSR came in like I said before, but I went to remove the old relay and what do ya know. all the wires shoot thru the connector and the wax holding the wires in, crumbles out. welp, lools like the harness is trash...

I decided to just push the connectors onto the relay prongs and hot glue for testing purposes...car wouldn't start. wtf. swapped back the oem relay and car fires right up. I guess a bad relay out the box?

otoh, the positive wire was corroded at the connector. I figured I could chop all the connectors off and replace them with butt connectors and use the generic relay I bought last week.

after the new generic relay was all hooked up, good to go, I hot glued it to the side of the power steering reservoir and a ziptie just in case. car fires right up, sweet. go on a test drive and....balls. same freaking thing. it stumbled 3 times in 6 miles. the hesitation off idle is still there, BUT I put it park to end my drive, disappointed and what not, and the idle shoots up to 1500+. tap the gas, rises higher and falls back to 1500. turn the car off and crank back up, normal idle around 850-900. I didnt mess with the throttle at all, or tps. tps still clicks.

TL;DR - replaced OEM harness and relay with butt connectors and generic relay. problems still present, also weird high idle after test drive. not sure if it will come back or not.

Could some foreign matter such as oil be going through the maf? An oil or water droplet will cool the hot-wire much more than air for a brief moment causing the ECU to inject more fuel

sounds like its possible...but my turbo has no oil coming out, the hose after the AMM isnt oily. this is my 2nd turbo and the same problem. I'm not sure how water (coolant?) could get there.

My car has been doing this for years. Still havent found out why. I replaced every part in the thing as well even with new stuff multiple times. I gave up and invested in Mega Squirt hoping it will fix the problem. Havent finished the wiring yet but soon it will be done and I am hoping that it is fixed.

The only thing I Have yet to try is a new computer. Maybe give that a try if you can find one. Keep me updated in a Private Message if you figure it out.

Good luck!

At least I'm not crazy. Will do, eventually I was planning to upgrade my chipped 563 ecu with a chipped 9xx. So maybe that'll happen sooner than later. Checking o2 sensor next, then I guess ecu is left..

I bought a new Bosch O2 and didn’t change anything. Try the computer sooner than later.

So ive acquired another ecu, a lh2.4 turbo 954, but ive been way to busy to mess with anything. My "super short" vacuum lines from my boost controller makes it impossible to take out without a longer vacuum line. Obviously I cant throw a stock ecu in with 15 psi...and for some reason my MBC can only take my psi's down to 10. As soon as my schedule dies down ill replace the line and swap ECUs to see if my symptoms go away.

It hasn't seemed to change at all. Going on a little over a year of the same problem

YASSSSSSSSSSSS...the problem has finally went away and hopefully will never come back. The culprit seems to be the original 5xx fuel ecu. I FINALLY popped the "known good" 9xx turbo ecu that I had in and immediately from the start up you can tell a difference. No more hesitation from an idle and no more random rich misfires while cruising! It's amazing to finally drive the car and have it drive the way it should. 120 miles down, hopefully thousands to go.