I_s2k Posted February 25 Author Share Posted February 25 Okay, warrantied the old MAP and put a different one on, replaced the grommet for the brake booster, and made the two gaskets for the EGR and still no dice. And this is with everything plugged in. It will still fire up with the Vacuum line unplugged from MAP sensor. Is it possible that I’m just getting junk sensors? As soon as I start to plug the vacuum in, the ISA or whatever it’s called will retract a bit I’m just guessing that’s because the MAP is sending the ECU bad readings if the MAP is bad. I find it kinda odd that it’s even idling kinda nice even with the vacuum disconnected. Link to comment Share on other sites More sharing options...
Comanche1 Posted February 25 Share Posted February 25 Same problem with my 87 2.5. Replaced my original map sensor with a Chinese 16.00 one from Amazon and it’s the best it’s ever run…so far. Link to comment Share on other sites More sharing options...
I_s2k Posted February 25 Author Share Posted February 25 1 minute ago, Comanche1 said: Same problem with my 87 2.5. Replaced my original map sensor with a Chinese 16.00 one from Amazon and it’s the best it’s ever run…so far. By chance do you have a link or name? I’m on Autozone #2. Link to comment Share on other sites More sharing options...
Ωhm Posted February 26 Share Posted February 26 4 hours ago, I_s2k said: 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. Isn't C218_B=MAP Output and C218_A=MAP Ground? Link to comment Share on other sites More sharing options...
I_s2k Posted February 26 Author Share Posted February 26 5 minutes ago, Ωhm said: Isn't C218_B=MAP Output and C218_A=MAP Ground? I believe so but I was trying to see the resistance going to the MAP. I’m trying to find the website I got the info off of for reference. Link to comment Share on other sites More sharing options...
I_s2k Posted February 26 Author Share Posted February 26 10 minutes ago, Ωhm said: Isn't C218_B=MAP Output and C218_A=MAP Ground? Here we go. I was going based off of this to check voltage and I believe I got the the ohm procedure off of cruiser54 tips if I remember correctly. Link to comment Share on other sites More sharing options...
Ωhm Posted February 26 Share Posted February 26 16 minutes ago, I_s2k said: I’m trying to find the website I got the info off of for reference. https://www.lunghd.com/Tech_Articles/Engine/Basic_Sensors_Diagnostics.htm Link to comment Share on other sites More sharing options...
I_s2k Posted February 26 Author Share Posted February 26 Just now, Ωhm said: https://www.lunghd.com/Tech_Articles/Engine/Basic_Sensors_Diagnostics.htm Yeeee, that’s it Link to comment Share on other sites More sharing options...
Ωhm Posted February 26 Share Posted February 26 Not sure exactly what I'm trying to do here, but with C218 connected, backprobe C218_C with (+) and use battery negative for (-). With KEY ON check for 5.0vdc. If you have ≈5vdc on C218_C, START ENGINE with MAP vacuum hose disconnected. Watch DVOM. Should hold near ≈5vdc. Now plug in MAP hose, watch DVOM, does ≈5vdc reading drop to 0vdc? Link to comment Share on other sites More sharing options...
I_s2k Posted February 26 Author Share Posted February 26 15 hours ago, Ωhm said: Not sure exactly what I'm trying to do here, but with C218 connected, backprobe C218_C with (+) and use battery negative for (-). With KEY ON check for 5.0vdc. If you have ≈5vdc on C218_C, START ENGINE with MAP vacuum hose disconnected. Watch DVOM. Should hold near ≈5vdc. Now plug in MAP hose, watch DVOM, does ≈5vdc reading drop to 0vdc? Okay I’ll have to check as soon as the new MAP sensor comes in, went ahead and ordered a cheap one off Amazon that had good reviews and returned the Autozone one. I can test with the OE sensor. Link to comment Share on other sites More sharing options...
Ωhm Posted February 26 Share Posted February 26 22 minutes ago, I_s2k said: I can test with the OE sensor. That will work. Looking for the 5vdc Supply Voltage (C218_C) to drop out when vacuum is connected to MAP. Link to comment Share on other sites More sharing options...
I_s2k Posted February 26 Author Share Posted February 26 32 minutes ago, Ωhm said: That will work. Looking for the 5vdc Supply Voltage (C218_C) to drop out when vacuum is connected to MAP. For sure….assuming that the voltage drops out, what would that tell me? I’m assuming something wrong with the MAP correct? I’m at gym right now, will test when I get home. Link to comment Share on other sites More sharing options...
Ωhm Posted February 26 Share Posted February 26 1 hour ago, I_s2k said: For sure….assuming that the voltage drops out, what would that tell me? 22 hours ago, I_s2k said: 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. When you mentioned C218_B (MAP Output) was showing 0.05ohms to (-) battery terminal make me think of Short to Ground (STG). If true, suspect ECU. Link to comment Share on other sites More sharing options...
I_s2k Posted February 26 Author Share Posted February 26 28 minutes ago, Ωhm said: When you mentioned C218_B (MAP Output) was showing 0.05ohms to (-) battery terminal make me think of Short to Ground (STG). If true, suspect ECU. Okay for sure, thanks. Unfortunately I can’t today as the wind is horrible right now but when I can I’ll do that and report back. Link to comment Share on other sites More sharing options...
Comanche1 Posted February 27 Share Posted February 27 On 2/25/2024 at 3:18 PM, Comanche1 said: Same problem with my 87 2.5. Replaced my original map sensor with a Chinese 16.00 one from Amazon and it’s the best it’s ever run…so far. Ok. Follow up. Not so good today. Still intermittent though. Perfect on minute stalls and bucks the next. Can go for 50 miles flawlessly! Link to comment Share on other sites More sharing options...
Comanche1 Posted February 27 Share Posted February 27 Anyone seen the egr valves stick, causing poor idle? Link to comment Share on other sites More sharing options...
eaglescout526 Posted February 27 Share Posted February 27 2 hours ago, Comanche1 said: Anyone seen the egr valves stick, causing poor idle? Not unheard of. Link to comment Share on other sites More sharing options...
I_s2k Posted March 1 Author Share Posted March 1 On 2/26/2024 at 12:06 PM, Ωhm said: When you mentioned C218_B (MAP Output) was showing 0.05ohms to (-) battery terminal make me think of Short to Ground (STG). If true, suspect ECU. So got a quick chance to throw in a 3rd MAP and I’m wondering if maybe the ECU is shot, I don’t have the chance today to hook a voltmeter up to it to verify again with this MAP but any last ditch efforts you can think of that I can try? Also if we’re assuming it is ECU, anyone have a line on a brand used one or a reliable repair service? Link to comment Share on other sites More sharing options...
GonzoTheGreat Posted March 1 Share Posted March 1 I think we should go back to the fact that it could idle with the MAP unplugged. If someone adjusted the ISA to compensate for that, and with the brake booster grommet leak, and others, the ISA will not be set for a properly functioning vacuum system. when you are 100% sure that all vacuum leaks are gone (if you don’t have a gauge, use starting fluid, propane, etc) then you need to make sure the ISA is adjusted correctly. Before spending more time and money on sensors, I would throughly go over the vac system and ISA. Link to comment Share on other sites More sharing options...
I_s2k Posted March 1 Author Share Posted March 1 41 minutes ago, GonzoTheGreat said: I think we should go back to the fact that it could idle with the MAP unplugged. If someone adjusted the ISA to compensate for that, and with the brake booster grommet leak, and others, the ISA will not be set for a properly functioning vacuum system. when you are 100% sure that all vacuum leaks are gone (if you don’t have a gauge, use starting fluid, propane, etc) then you need to make sure the ISA is adjusted correctly. Before spending more time and money on sensors, I would throughly go over the vac system and ISA. It is possible that the ISA could be adjusted to account for the MAP being unplugged but I do know for a fact that the ISA does work. When I start the jeep with the MAP vacuum unplugged and then go to plug the vacuum back in while its running, the ISA plunger will start to retract. I will note that the motor does not immediately cut off, it slowly idles down till it stalls. I did replace the grommet for the brake booster as well, the diaphragm in the booster is definitely still leaking though but that doesn't cause any issues until i depress the brakes and than it starts to idle up as expected. Link to comment Share on other sites More sharing options...
eaglescout526 Posted March 1 Share Posted March 1 Can you post a pic of the ISA with the engine off and running? Link to comment Share on other sites More sharing options...
I_s2k Posted March 1 Author Share Posted March 1 1 hour ago, eaglescout526 said: Can you post a pic of the ISA with the engine off and running? When i get home, yes. If my memory serves me correct....the hex head is at least touching the throttle. I have no idea if it is fully extended or not but as mentioned in another thread. When the Jeep stalls out, the ISA motor does its 3 taps and i can feel it move the gas peddle as its engaging. But it's also safe to say that at one point the PO has done something with it as the retainer on the plug is broken off and was like that before I looked at it. I also wanted to ask, is there anything different I would need to do with the procedure for adjusting the ISA considering the MAP vacuum will be unplugged to get it running and up to operating temp? Link to comment Share on other sites More sharing options...
eaglescout526 Posted March 1 Share Posted March 1 With the MAP plugged in, are you able to manually open the throttle and get a good idle or will it have issues if you do that? id manually open the throttle from the engine bay as you can open it more slowly by hand than with your foot. Link to comment Share on other sites More sharing options...
I_s2k Posted March 1 Author Share Posted March 1 18 minutes ago, eaglescout526 said: With the MAP plugged in, are you able to manually open the throttle and get a good idle or will it have issues if you do that? id manually open the throttle from the engine bay as you can open it more slowly by hand than with your foot. With MAP vacuum plugged in, I have to rev it up pretty high for it to stay running, no tach so I have no idea how high it actually goes but audibly I have rev it up and hold it. It also hunts for an RPM, I can't get it to sit at a constant speed. I plan on buying a tach and connecting per your write up for the ISA. Link to comment Share on other sites More sharing options...
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