xj8588

ok so im kinda new to the jeep world. i bught my first cherokee about 8 months ago (85 cherokee. gutless 2.8 typical body rust, but for $52 i couldnt pass it up. the 85 got a homade 4inch lift some 33s did great, still does dispite the anemic engine and some deathwobble issues maybe ill make a built thread for it to show what it has become. back to the point. i caught the jeep thing and decided to buy 2 more in the past month, one 95 as a parts rig and another 85 as my new off road/ sometimes dd jeep, i gave the 85 to my gf. i bought the 88 from an older gut who only used it for towing a small camper thing every now and then. he kept it in great shape, apears the he followed up on matinence and bless his heart he tried his best to patch up the rust spots (fiberglass eghhh) (wich are going to be repared better later on lol) i gave $276 for it and he almost seemed guilty for taking it all. but idc i like it, great potential. back to the story, it diddnt run, was sitting for a little over a year, needed a starter (parts rig) and the battery was shot. we towed it to my friends house whom lives in the same area, got it running (poorly) but enough to get it home (almost leagly ) it has the 4.0 aw4 everything looks mechanically fine and nothing seems to be missing. my problem therein is the renix system. ive got a terrible high idle, goes straight to 3000 when i start it up. ive read 100 time to check, clean or replace all the grounds and heva done so with surgical precision(exeration but i did my best) i replaced most of the cables even added a few extras, i changed the alternator with a new one (i forgot to mention the old one was shot) i cleand and re cleaned the throttle body, replaced the injectors, checked everywhere for vacuum leaks and still reves up like a stupid kid in his civic (no offence at all to anyone who owns a civic and dosent think its a 10 second race car). ive read many fourms on this topic and i still have no luck diagnosing the problem. ive become so frustrated with the thing im considering just taking the entire wireing harness out, sensors, distributor, and anything else fuel/ing system related and converting to propane. new older style distributor and ill get a tcu/ new shifter from radesines.com and be done with it already. i welcome any advise in fixing the renix or steering me in atleast a direction with my poor little jeep. im going to make a build thread on it as soon as it runs again. im think 6.5 long arm d44 from a scout and maybe a d300 twin stick ive got around here somewhere, plus a whole crap load of custom stuff. thanks for the help in advance. ill get some pictures up as soon as i figure out how.

Vibraslapp

I am currently trouble shooting my renix as well. I can tell you things I am learning along the way. Do you know how to read it's codes?

trans_am7935

xj 8588, your problem is the TPS sensor (AKA the Throttle Position Sensor) i had an 88 and when it gets wet it dies and needs replaced. unfortunutly it is expensive, like $80 or so. but that should fix your problem. you have 2 sensors directly infront of your throttle body, it is the one on the right with the little adjustable tab sticking out the back. the sensor you want is the one on the right in the picture with 3 wires coming out of it. replace that and you will be good


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xj8588

ouchh they are expensive.. but whatever i have to do to get it running. ill pick one up today or tomorow if i get a chance. so these things are not very durable when wet? thats not going to fair very well my plans for this jeep will most definatly involve it being submirsed at some time or another. hmm any way to seal up the renix system or would i be better off transplanting my 95 parts jeep engine and harness into it..or better yet getting a painless wiring harness for it? maybe just tear the renix out and go all out and get a propane setup? im not sure what the best path for me to take is.. i like the simplicity of the renix but it needs to be durable. ill do what it take to get it running for now but i hate to throw money at it if its not going to be trail worthy. also would it be worth a try to convert the closed cooling system over to the open one? my radiator has a small hole (i patched it but i dont need it to fail out in the woods somewhere) plus i have an anoying overheating issue. i know its probaly just air or something in the system. i did buy another thermostat and gasket ill drill a small hole in it...exc exc you guys already know. thanks for the help so far. still dont know how to work the pictures though

alpine.adrenaline

Renix ('87-'90) Fuel/Emissions systems are pre OBD and do not generate codes. Diagnosis of almost any problem with a Renix system can be done with a multimeter at the "D" terminals next to your power distribution block (passenger side between your battery and firewall). These will look like female sockets for a plug and should be covered by two yellow or orange rubber lids.
Check out http://www.lunghd.com/Tech_Articles/...iagnostics.htm for Renix diagnostics.

XJ8588, I can almost guarantee you have an intake leak. You can test the TPS first by throttling the lever with your finger to see if there's a response from the engine. The ECU should try to compensate by adjusting fuel/air mix. I'd get an unlit propane torch and use it as a wand to locate the intake leak. When you get the torch near the spot where it is drawing in excess air, the engine's RPM will change as it burns the propane. You'll know where to start, that way. Most of the time it's a loose bolt where your intake manifold meets your cylinder head. Good luck!

xj8588

sounds like an easy test to me, im going to go try it now and see what happends. looks like they arnt very hard to change. if it is the problem any tips or tricks to change the intake gasket? wile i have it apppart anything else matinence wise or other helpful modifications i can make? i appreciate the help alot guys.

xj8588

ok so i tested the intake manifold gasket with an unlit propane torch and nothing changed, no change in idle at all. i messed with more wires, cleaned the vacuum lines out with some carb cleaner, checked and rechecked all the wire conectors, fixed an exhaust leak, i changed the thermostat, flushed the cooling system, wich wasnt all that dirty, and messed with the electric fan (wasnt working but i never noticed what with the high (really high) idle. so now no overheating. and the idle went down too still not where its spposed to be. searches up and down from almost a stall to around 1500. i took it for a test drive just down a back road and it runs fine when on throttle but still crappy at idle. maybe a sensor? tps? how about the coolant temp sensor? i read all the diagnostics and other information from this fourm and the ones provided im the links you guys have shown me (thank you by the way). i happy to be making progress, the other jeep isnt doing so well- carb problems so maybe this one will be put on the street sooner then i thought. still worried about the reliability of this simple yet 22 year old jeep renix thing. dont get me wrong i love older vehicles this is my newest vehicle yet... and the first with fuel injection... im sure many have taken these era jeeps of roading befor what do i need to do to make it survive?

littleredXJ

I was out trail riding one day and stalled the motor on my 90 xi. When it started back up it was running at 3k. I hit the idle air control valve lightly with a wrench and that fixed it. I took the valve off the throttle body and cleaned it and haven't had an issue since then. Bottom line, check the iac valve on the throttle body, it is probably bad or stuck open causing a high idle.