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post #1 of (permalink) Old 11-19-2003, 11:27 AM
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MAP sensor & EGR Valve question


I posted this on the cherokee forum but thought I'd put it here to for mor visibility. I have some questions relating to the MAP sensor and EGR valve and desperately need some help.

I have an 89 wranger with a 4.0 EFI motor taken from a 91 cherokee. It will not pass emissions. My local shop says that the Nx is too high. And they say it's missing the EGR valve. They tried to correct the test results by replacing the O2 sensors to no avail.

some background on the vehicle...the engine swap was done back in 1994 and I've had it garaged mostly since 1998 when I last had it inspected (it passed fine then).

Is it possible the shop that did the swap did not install the EGR valve? Did the 91 cherokee 4.0 even come with an EGR valve?

Also, if it is missing the MAP sensor could this be another possible cause? I've been reading that the map sensor function is to calculate the amount of fuel to go into the engine... I'm guessing that if that is missing then the motor may be running too rich or lean.

How/Where does the MAP sensor install? Same for the EGR valve... and how much $$$ roughly?

Would be great to get this tuned properly and passed emissions.

THank you,


1989 Jeep Wrangler
*came with 2.5 150
now has 4.0 242 EFI
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post #2 of (permalink) Old 11-19-2003, 12:02 PM
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Re: MAP sensor & EGR Valve question

It wouldn't run without a map sensor. If it had an egr valve, it will need it to pass emmissions. The egr valve lets in exhaust gas to cool combustion temperatures below the level at which N0x is formed during the combustion process. You need an emissions schematic for the 91 donor vehicle to make sure all the emission controls are in place. Chilton or Haynes manual? Factory emissions controls manual?
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post #3 of (permalink) Old 11-19-2003, 09:54 PM
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Re: MAP sensor & EGR Valve question

Here in N.C. the inspection station has to have the manuals to show what came on the veheicle being inspected or in your case the transplant. [img]images/graemlins/beach.gif[/img]
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post #4 of (permalink) Old 11-21-2003, 03:46 AM
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Re: MAP sensor & EGR Valve question

Check my reply on the other forum.
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