Broke Man With Tools (engine swap)
#76
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HEY! Good to hear back from you. The MAP can get intake manifold vacuum from anywhere. Since it's not plugged into the little rubber dealie on the valve cover side of your throttle body, you might have a vacuum leak there. (down at the base). Plug that o0r fit a tube in there for the MAP.
#77
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Join Date: Aug 2011
Location: Nor-Cal Coast
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Year: 90,84
Model: Cherokee
Engine: 4.0,2.5
OK, the "throttle body" is not much more sophisticated than your can. It's plate just controls air into the intake via your foot. One exception, at idle with the plate closed the rubber nose of the IAC motor, (pintle) controls air for idle. The TB just controls air flow and has the TPS on there to tell the puter where your foot is. Old school, "choke" does not apply here since the fuel actually comes from the injectors controlled by the computer.
The 02 sensor is not your problem here. The puter will make it run on default settings if it's fubar, best as I understand. Of course you need to get your pipes hooked up, I'm not thinking that should keep it from running.
The MAP is supper crucial to run at all. If your foot opens the throttle plate, intake manifold vacuum plunges. That drop in intake vacuum tells the MAP to dump more fuel, (by making injector pulse with longer). The MAP needs to be good and have intake vacuum for it to work at all. That "rough" mix is then trimmed by the puter with knowledge of the engine temp and 02 sensor readings RPM ect and stuff.
I wouldn't mind a pic of the VC side of your TB. Also, you know how to jump your fuel pump relay, did you try that? I had high hopes that that would make it run......I'm not suggesting there is a problem with the fuel pump, I thought it sounded like it ran with the rail pressurized from cranking/starting, then the FPR lost ground when you went to run. Jump the darn relay and run it would you?
The 02 sensor is not your problem here. The puter will make it run on default settings if it's fubar, best as I understand. Of course you need to get your pipes hooked up, I'm not thinking that should keep it from running.
The MAP is supper crucial to run at all. If your foot opens the throttle plate, intake manifold vacuum plunges. That drop in intake vacuum tells the MAP to dump more fuel, (by making injector pulse with longer). The MAP needs to be good and have intake vacuum for it to work at all. That "rough" mix is then trimmed by the puter with knowledge of the engine temp and 02 sensor readings RPM ect and stuff.
I wouldn't mind a pic of the VC side of your TB. Also, you know how to jump your fuel pump relay, did you try that? I had high hopes that that would make it run......I'm not suggesting there is a problem with the fuel pump, I thought it sounded like it ran with the rail pressurized from cranking/starting, then the FPR lost ground when you went to run. Jump the darn relay and run it would you?
Last edited by DFlintstone; 04-07-2019 at 07:46 PM.
#79
Newbie
Thread Starter
So guys, its over. We've done it. The reason why it wasnt working was because the ECU was shot. $40 later at the junkyard and she's running a plenty. I still need to button up a few things but i did some burnouts in the parking lot just to make sure.
Things to get:
-catalytic converter
-muffler
-u-joint for front drive shaft
-4WD gear selector bracket???
-And a bunch of cosmetic stuff
I am truly grateful for all of your help and motivation. I don't think I could have done it without you guys. You are the real MVPs.
Side Note:
Here is the video I watched that gave me a clue what the problem was.
Things to get:
-catalytic converter
-muffler
-u-joint for front drive shaft
-4WD gear selector bracket???
-And a bunch of cosmetic stuff
I am truly grateful for all of your help and motivation. I don't think I could have done it without you guys. You are the real MVPs.
Side Note:
Here is the video I watched that gave me a clue what the problem was.
Last edited by DRKHRT; 04-21-2019 at 12:28 PM.
#80
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Join Date: Mar 2016
Location: Oklahoma
Posts: 621
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Year: 1992
Model: Cherokee
Engine: 4.0L L6 PowerTech (stock)
What was your total? It'd be great for you to do one post at the end of this documented your steps and dates and costs with a total at the end. It be a nice conclusion.
#82
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Thread Starter
#83
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Thread Starter
#84
Senior Member
Good to hear it is running - that made me smile. You had some tough challenges and a less than ideal "garage" space but you worked through the issues. Great accomplishment. I admire what you did.
#86
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Join Date: Nov 2017
Location: Groton, MA
Posts: 3,695
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207 Posts
Year: 1995
Model: Cherokee(XJ)
Engine: I6 4.0L
Woooooo!!! NICE JOB man!!!!!! So happy to hear you've got the old beast up and running again! It's a hell of an accomplishment and a heck of a lot of work.
Also thanks for the follow up reports as well. It's such a huge help to the rest of the XJ loving community and nice to know for all the folks here that have been following your progress.
You could get one of those "built not bought" bumper stickers - you've more than earned it!!
Also thanks for the follow up reports as well. It's such a huge help to the rest of the XJ loving community and nice to know for all the folks here that have been following your progress.
You could get one of those "built not bought" bumper stickers - you've more than earned it!!
#87
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Join Date: Aug 2011
Location: Nor-Cal Coast
Posts: 10,489
Likes: 0
Received 17 Likes
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17 Posts
Year: 90,84
Model: Cherokee
Engine: 4.0,2.5
Woooooo!!! NICE JOB man!!!!!! So happy to hear you've got the old beast up and running again! It's a hell of an accomplishment and a heck of a lot of work.
Also thanks for the follow up reports as well. It's such a huge help to the rest of the XJ loving community and nice to know for all the folks here that have been following your progress.
You could get one of those "built not bought" bumper stickers - you've more than earned it!!
Also thanks for the follow up reports as well. It's such a huge help to the rest of the XJ loving community and nice to know for all the folks here that have been following your progress.
You could get one of those "built not bought" bumper stickers - you've more than earned it!!
Fun U tube clip! Really? Your 92 has an under dash ECM? I'd thought it would have an under hood PCM. (power control module), being post 90.
Last edited by DFlintstone; 04-29-2019 at 07:05 PM.
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