tdtony Posted July 9, 2023 Share Posted July 9, 2023 I've attached a video, but I don't know if it comes through well. The truck idles between 750-1000 RPM, but occasionally it drops under 750 RPM and sound like its about to stall, then it jump back to 750-1000 RPM I've gone through post on the forums about idling and stalling issues, but so far nothing has worked for me. So far I've: checked Bolts on the intake manifold are tight. New IAC replaced the Vacuum harnesses new fuel pump/filter new spark plugs/wires new Volvo 746 injectors disconnect the vacuum line to the EGR solenoid and plug it Cruiser Tips I've done: 1 – Ground refreshing 2 – C101 connector refreshing 3 – Connector and relay/receptacle refreshing 5 – Checking sensor grounds 6 – Sensor ground upgrade 8 – TPS testing and adjusting 11 – Throttle body and IAC cleaning Any suggestions on what I should check next 2023558656_PXL_20230709_192757433_TS2.mp4 Link to comment Share on other sites More sharing options...
cruiser54 Posted July 10, 2023 Share Posted July 10, 2023 Your EGR valve could not be seating fully and cause an internal vacuum leak even with the hose plugged. You might want to make sure your throttle body is set correctly and that the o-ring on your IAC is good. Link to comment Share on other sites More sharing options...
pizzaman09 Posted July 12, 2023 Share Posted July 12, 2023 I'd also consider the condition of your O2 sensor. My truck did similar things and it was swapping out my Bosch O2 sensor for an NKT that fixed it. Link to comment Share on other sites More sharing options...
tdtony Posted July 15, 2023 Author Share Posted July 15, 2023 Thanks for the suggestions cruiser and pizzaman, I'll go check on em tomorrow if it doesn't rain all day. Also I was checking my fuel pressure at the rail yesterday and noticed that when the rpms drop the fuel pressure increases from 31 psi to 34 psi and then goes right back to 31 psi when the idling returns to normal. I don't know if that means anything, or if that helps narrow down the potential cause. Link to comment Share on other sites More sharing options...
tdtony Posted July 15, 2023 Author Share Posted July 15, 2023 On 7/10/2023 at 12:31 AM, cruiser54 said: Your EGR valve could not be seating fully and cause an internal vacuum leak even with the hose plugged. You might want to make sure your throttle body is set correctly and that the o-ring on your IAC is good. What do you mean when you say the throttle body is set correctly? Link to comment Share on other sites More sharing options...
cruiser54 Posted July 15, 2023 Share Posted July 15, 2023 we're actually gonna save that til later. Link to comment Share on other sites More sharing options...
tdtony Posted July 20, 2023 Author Share Posted July 20, 2023 I replaced the gasket for the egr and reseated it. I also replaced the o-ring on the IAC. No change. I checked the O2 sensor according to this post by cruiser https://www.cherokeeforum.com/f2/how-test-o2-sensor-renix-155971/#post2160456 I only have a digital multimeter so I couldn't test O2 sensor voltage, but I got 11.9 volts on the orange wire 5.0 volts on the black wire 0.5 ohms on the ground Any ideas for next steps? Is it time to make sure the throttle body is set correctly? And it's that tip 14? https://cruiser54.com/?p=94 Link to comment Share on other sites More sharing options...
cruiser54 Posted July 20, 2023 Share Posted July 20, 2023 Yes. Tip 14. But, are you sure the EGR is sealing internally? Did you test it for that? Best way to test the O2 sensor is with the REM or doing an ohms test across the red and black wire with the sensor unplugged. I think 8 ohms is good? Link to comment Share on other sites More sharing options...
tdtony Posted July 20, 2023 Author Share Posted July 20, 2023 12 hours ago, cruiser54 said: Yes. Tip 14. But, are you sure the EGR is sealing internally? Did you test it for that? Best way to test the O2 sensor is with the REM or doing an ohms test across the red and black wire with the sensor unplugged. I think 8 ohms is good? Oh sorry, i misunderstood. I thought you meant checking if the EGR was sealing to the manifold. How would I test if the EGR is sealing internally? Is REM renix engine monitor? https://nickintimedesign.com/shop/ I don't have one yet, but it's on my list Link to comment Share on other sites More sharing options...
cruiser54 Posted July 20, 2023 Share Posted July 20, 2023 take it off. See if you can blow from the pintle side and air goes through the valve. Your lips will be black............ Link to comment Share on other sites More sharing options...
tdtony Posted July 24, 2023 Author Share Posted July 24, 2023 Took the EGR valve off and I could blow air through it. I'll order a new one and see if that fixes it! Link to comment Share on other sites More sharing options...
cruiser54 Posted July 24, 2023 Share Posted July 24, 2023 good luck with that..... Link to comment Share on other sites More sharing options...
tdtony Posted July 24, 2023 Author Share Posted July 24, 2023 13 minutes ago, cruiser54 said: good luck with that..... Looking online most of the reviews of aftermarket EGR valves are pretty bad, any recommendations or an I better off trying to find a good one at a junkyard? Sorry, didn't see the post you linked Link to comment Share on other sites More sharing options...
TurboedMJ Posted August 11, 2023 Share Posted August 11, 2023 I am having the same issue, done everything you have, and replaced my O2 sensor, IAC, TPS and fuel pump/filter. Haven't replaced injectors yet, doesn't sound like that is the issue. Link to comment Share on other sites More sharing options...
cruiser54 Posted August 11, 2023 Share Posted August 11, 2023 Have you both removed and tested your EGR valve? Link to comment Share on other sites More sharing options...
TurboedMJ Posted August 11, 2023 Share Posted August 11, 2023 I haven't. That's next. Link to comment Share on other sites More sharing options...
OldSch88L Posted August 11, 2023 Share Posted August 11, 2023 Pretty interesting topic... I have a REM II, and noticed the same symptoms as the OP, but the difference is I could monitor all the engine parameters. Turns out it always happens when the REM says that the EGR is ON, at idle. As soon as the EGR turns off, the truck runs smooth again. And actually, the EGR cycles on and off a lot on idle. The EGR valve isn't stuck, and I've cleaned it, and it's also an original one. I also don't know if it's related, but I always have a lean condition on open loop that stabilizes in closed loop. Short term fuel trims always at 128, and long term at around 91 lately IIRC. Haven't found a vacuum leak yet, and all that data is from a 1988 MJ, 2.5L manual, with a 1986 manual 2.5 ECU. Hope that helps. Link to comment Share on other sites More sharing options...
TurboedMJ Posted August 11, 2023 Share Posted August 11, 2023 42 minutes ago, OldSch88L said: Pretty interesting topic... I have a REM II, and noticed the same symptoms as the OP, but the difference is I could monitor all the engine parameters. Turns out it always happens when the REM says that the EGR is ON, at idle. As soon as the EGR turns off, the truck runs smooth again. And actually, the EGR cycles on and off a lot on idle. The EGR valve isn't stuck, and I've cleaned it, and it's also an original one. I also don't know if it's related, but I always have a lean condition on open loop that stabilizes in closed loop. Short term fuel trims always at 128, and long term at around 91 lately IIRC. Haven't found a vacuum leak yet, and all that data is from a 1988 MJ, 2.5L manual, with a 1986 manual 2.5 ECU. Hope that helps. How does it do at 2k rpm steady? Same issues? Link to comment Share on other sites More sharing options...
cruiser54 Posted August 11, 2023 Share Posted August 11, 2023 why don't you guys put a block-off plate at the EGR? Link to comment Share on other sites More sharing options...
TurboedMJ Posted August 11, 2023 Share Posted August 11, 2023 1 hour ago, cruiser54 said: why don't you guys put a block-off plate at the EGR? I am looking into it. Can I test the egr valve with an air compressor? Link to comment Share on other sites More sharing options...
cruiser54 Posted August 11, 2023 Share Posted August 11, 2023 No. Just take it off and make sure no air can get around the pintle. You can use your mouth to check it. I may have a lead on a stainless steel shim that replaces the gasket and seals off the EGR. Will look stock. Link to comment Share on other sites More sharing options...
TurboedMJ Posted August 11, 2023 Share Posted August 11, 2023 My egr was cut off by the previous owner... Link to comment Share on other sites More sharing options...
cruiser54 Posted August 11, 2023 Share Posted August 11, 2023 The EGR valve itself was removed and blocked off? Link to comment Share on other sites More sharing options...
TurboedMJ Posted August 12, 2023 Share Posted August 12, 2023 Looks like it. There is a plug in the header where I think it would go. Link to comment Share on other sites More sharing options...
cruiser54 Posted August 12, 2023 Share Posted August 12, 2023 Is the EGR installed on the intake manifold? Is there a plug in the intake manifold where the other end of the EGR tube would thread in? Link to comment Share on other sites More sharing options...
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