I_s2k

Wire brushed the nut, threads and block for the block connection as well as cleaned the strap. Also cleaned, wire brushed both ends of the strap and the bolt/firewall connection. Also just looked the front PCV. Cleaned it up a little bit and the little check in it moves freely. The rear one looks pretty nasty but I didn’t wanna spray anything up into it.

So testing the connector for the MAP, I’m getting 0.05ohms when connecting + to B and - to - battery terminal. The ground for this sensor(dipstick) has been cleaned and wire brushed as well.

Sweet, like I’ve said before, these are all firsts for me but now I know for that’s not my issue. Jeep still won’t stay running unless MAP Vacuum is unplugged. Gonna start testing other sensors and seeing what I get as well as just once overing vacuum lines etc.

Little update, got it adjusted to 4.65v WOT going from + at A and - at B. With probes is same terminals it’s also at 0.86 closed.

Alrighty so I tested the TPS just now. B to C I’m getting 5v, I saw two different write ups on how to test but this one made the most sense to me since the readings were closer to what I’m getting. But anyways, B to C is 5v, moving throttle does not change this value and A to B is 4.91v WOT and 1.05v closed. I saw that WOT should be 4.6-4.7v for M/T. Gonna attempt to adjust it but I feel like this wouldn’t be enough to cause the Jeep to not stay running.

Okay I’ll look into it! Thanks and that’d be appreciated!

I have not done a compression test but I can say that the oil is coolant free and vise versa for the coolant. I have not checked either the front or rear CCV’s, they’re the weird canister deals. Do they just pull out like the plastic elbows thatre on the 4.0’s? Wouldn’t hurt to attempt in cleaning them regardless. I forgot to mention that I also replaced the TPS and added that to the list of things done. How do you adjust them?

Hey guys, so I’ve been battling a rough idle, situation on an 86 2.5/4 speed I acquired a little over a month ago. So far what’s been done….. -new gas -new fuel filter -new map sensor -rebuild throttle body -cleaned off CPS at bellhousing -cleaned all connectors and relays -new cap/rotor/plugs/wires -4 little vacuum lines have be replaced at the bottom of the TB -cleaned all grounds bumper to bumper -vacuum soft line to MAP replaced(was missing) -New TPS Id like to just throw money at it and replace everything but for now, this drivetrain isn’t staying and I’m wanting to swap eventually. I really just want to get it running with bare minimum put into it. The problem: The Jeep will startup everytime no problem but will only stay running with MAP vacuum unplugged(very poorly obviously). It will even drive with it unplugged but starts to hesitate/sputter/bog when any hard acceleration is put down. When the MAP vacuum is plugged in, the Jeep will start and immediately stall unless I have the throttle depressed pretty far and even then it surges(no rpm guage but the the rpm will audibly go up and down slightly). With the vac line unplugged and the Jeep running, I can plug the hose and it’ll stay running but as soon as I plug it into the MAP it dies(it does this with both the new MAP and OEM MAP sensors). I’ve traced every vacuum hose and some are dry rotted a bit but aren’t leaking, the Jeep is relatively all OE still and I still have the OEM MAP sensor as well. My question is, the grommet on the brake booster is shot and I plan I replacing tomorrow but is this enough to cause this issue? Also, for the “EGR Solenoid” or whatever it’s called on the passenger fender that has the two relays for the fuel system, is that supposed to have 1 or 2 vacuum hoses attached? Mine currently has one but I can’t find any unplugged hoses. Any tips or insight would be appreciated. Thanks! PS: I apologize if any of my terminology is bad, I’ve had 6 XJ’s, all of which are 96+ and all were 4.0’s so the renix and 2.5 deals are new to me haha.

I should also say that the backfire only happened when I was trying to keep it running with the vacuum plugged into the MAP.

Yea not like a bad backfire but it does do a little bit when I try to feed it too much gas. I unplugged the vacuum going to the map to get it to start and tried plugging it back in to see if it would run but once the vacuum is connected it immediatly starts to die. I’m leaning more towards the map. I verified the hard line going to the soft line is not clogged and as stated above, I cleaned the TB inside and out, maybe the MAP I got is no good? Wouldn’t be the first time.

Alrighty, got the throttle body cleaned inside and out, resealed the whole thing and even cleaned the bolt heads and threads. I replaced the TPS and double checked the plunger on the EGR and it seems to working fine. So far, no change. I will say that it runs significantly better now when it does run but I have to give it throttle to stay running but it’ll eventually die out and backfire.

Okay, will check either tomorrow or Monday and report back. The throttle body rebuild came in today.

Ah okay gotcha, what does it look like when stuck open? Hence I can’t keep it running long enough as is to check that. Like I said in other posts, the map sensor plugged in to vac prevents it from running. Also tried unplugging it electrically and it won’t even start.

It looks fairly new but I have not, I’ve also read up a little bit about how they operate. Care to explain what I should look for on it?

Haha no, it was relatively empty, pretty much in the red line and I tried to drain as much as I could out without dropping the tank. I added 10 gallons of new and a can of seafoam. Also a general update, I replaced the rubber block with 4 hoses and still no dice, I’m at a loss here as to why the MAP sensor, when the vacuum is plugged in, will cause the Jeep to not run. When vac is unplugged it starts and will even drive. I’m gonna grab a voltmeter tomorrow and go over sensors again. Does anyone have an electrical diagram for under the hood? I’ve noticed that I have a few plugs that either have dummy plugs in them or are just open so I’m wondering some are for options I don’t have or something.

Ah okay, interesting. When I replaced the plugs they werent wet with coolant although plug one had a lil oil on it but that could be from the valve cover gasket as its seen better days or from smoked rings. I'm gonna try and get as many hoses replaced as I have time for this weekend.

Well It definitely has a cracked or leaking diaphram leaking from in the brake booster and i need to start replacing vac hoses throughout as prolly more than 50% of them are dry rotted but as stated before, I just wanna do the bare minimum to get it running as this current drivetrain isnt staying. But I would not be surprised if the headgasket is shot and I'm pretty sure piston one rings are smoked. As of now, no coolant in the oil from the hand full of times I've ran it.

Sure! haha. I have no idea when it officially ran and was on the road running good, the tag that is on it currently is from 2016 so at least 8 years ago. However it does run and drive without the MAP plugged in, just very poorly. I've gotten it up to 3rd gear through its spits and sputters. I believe its still green. The radiator is full but the overflow is empty.

Would you happen to know off the top of your head what size they are?

Alrighty so last night I went ahead and unplugged the old MAP to verify that it still would start and run and that it did, still not very good but it stayed running. I replaced the MAP with a new one and unfortunately no dice. I can verify that the old one is the original and I havent thrown it away in case its not the problem but what do you guys think? I did notice the 4 short pieces of rubber that connect to the throttle body, does anybody know how likely those are to leak and if so, do you know the sizes so I can replace them? I also need to verify that the hard line that goes to the MAP isn't clogged. I will say that on the first start up with the new MAP, the Jeep wanted to run, it idled up and held an idle for a few seconds than eventually sputtered and died and now its back to running only when I hold the idle with the throttle. Even when I do that it surges, like a constant up down up down RPM wise. Unfortunately I have the dummy cluster so I couldnt tell you what RPM's it goes to.

hahaha my bad, I'm to all this 2.5 nonsense. I was pointed in the right direction at least! Good to hear! New MAP sensor is ordered and should be ready for pickup by the time I get off, I'll update if it makes a change at all. On a side note I did order a TBI "rebuild" and new TPS just in case. After looking at sensor yesterday, its a strong possibility that theyre all OEM or at least very, very old. The TPS is just a safety incase the MAP doesnt change anything and I figured the TBI rebuild wouldnt hurt. Those should be in next week!

I would imagine if you adjusted the IAC at all when something happened like with mine where I was missing the MAP hose, yea you’d probably have to adjust it again but I didn’t touch mine at all. I just thought it was funny that whenever the Jeep would stall, the throttle would physically move and create 3 taps.

Thanks all for the input. You are referencing the IAC? I did notice that when it would stall last night after trying to get it to run, I’m assuming the IAC was making the throttle “tap tap tap” after it would die.

Alrighty party people, so today I had the chance to once over the other side of sensors ie the cps, tps, etc and come to find out, the MAP sensor was missing the rubber hose as a whole. Can’t believe it took me this long to figure that out and I’ve looked at the MAP sensor several times😂 anyways…..went to the parts store and picked up a hose and reconnected it and now won’t stay running. I’m thinking the MAP sensor is either shot or clogged, any recommendations to brands of new ones? I know the “mopar is the best” speech but I’m not paying for an OE sensor for a motor I plan to rip out. I’d just like to get it running!

Ah okay, so hat clears up a few things thanks.