aliecks Posted October 28 Posted October 28 Alright, long story short I got a short bed 2.5L Comanche from my grandpa, he treated it well but he hasn’t drove it much the past few to more than few years.(Other than to deer camp and back once a year) So I’ve have it for a few months and I’ve decided to go for a Street Comanche clone type of deal with the help of ORG parts. Before I get too crazy with cosmetics I’ve been chasing a “stumbling idle” and/or high idle issue. I’ve scanned the forms and watched plenty of Nickintimes plus other creators. I have a Snap-on MT2500 and with my “expertise” lol I diagnosed the TPS being bad. I replaced it, set it to 4.64-4.65v at WOT, I replaced the EGR valve gasket and verified my ISA is functioning. Test drove it yesterday about 10-15 minutes and the truck did well. After getting to operating temp it was sitting at about 1000-1100RPMs with A/C off. Today I drove the truck home about 25-30 minutes county roads, again after operating temp at idle I would be sitting at 1000-1100RPMs. My stumbling idle issue is gone I’m assuming the EGRR gasket leak and the faulty TPS was causing that. I think my ISA is out of adjustment from previous mechanics messing with it causing my high idle. MY FINAL QUESTION: What is the actual procedure for adjusting the ISA on a 89? In my Chiltons manual it says the 89-90 doesn’t have idle speed adjustments and is controlled via computer…so is that right or do I go the unplugged ISA 3500RPM route? Or am I completely wrong? Anyways thank you for coming to my TED talk.
aliecks Posted October 28 Author Posted October 28 I’ll try this adjustment procedure, drive it home and report back later today or tomorrow with how it’s acting. Thanks
eaglescout526 Posted October 28 Posted October 28 No problem! That adjustment procedure is straight from an AMC|Jeep manual.
aliecks Posted October 28 Author Posted October 28 Alright, I got it adjusted and the first start up after plugging the ISA back in the truck , it sat at about 2000RPMs. I plan to take the ISA apart and see if I can figure anything out. To go back a little bit, I replaced my EGR gasket after a smoke test and seeing smoke escape from there, also while tightening that down I noticed I was missing the rear lowest manifold bolt/stud. Threw a bolt in there and after all of that the stumble/stutter seemed to go away and has been gone. I’m assuming I’m good on vacuum leaks but I’ll smoke test it again when I remove the ISA to verify. I’ve been smoke testing through the brake booster vacuum, if anyone has other places to test let me know!
aliecks Posted October 28 Author Posted October 28 Just checked my idle at cold, sitting at about 1900RPMs so it’s in the same ball park, from how it’s acting I’m thinking some of the gears are held up in the ISA making my adjustment incorrect. Will update when I get the ISA apart and inspected.
eaglescout526 Posted October 28 Posted October 28 Does the ISA return to start position after shut down?
aliecks Posted October 29 Author Posted October 29 Yes it extends after shut off. I opened it up and nothing looks broken(Gears and connections). No rust, and still has grease in it. I provided a couple pictures of the condition. Also re-checked my vacuum with a smoke test and all is good. Going to hook up the ISA to the truck again tomorrow and re-adjust it. Hopefully I’ll have better results.
aliecks Posted October 29 Author Posted October 29 Unsure if it’s been replaced, any recommendations on where to look next?
garyweb3 Posted November 2 Posted November 2 The plunger on my ISA never moves in either direction on my 2.5. What is supposed to control the action?
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