86 Cherokee acceleration problems

Hi all Back again. I am still having problems getting my 1986 Cherokee Pioneer with 2.46L engine and Throttle Body Injection, to give a smooth acceleration under load. Seems to be more pronounced during the lower part of the power curve. Downhill it seems to have great acceleration. (No Jokes Please) When it starts up a hill it slows down and depressing the accelerator pedal seems to make it bog down worse. Depressing the pedal to the floor seems to really cause it to bog down. If I downshift to a lower gear and get the RPMs up it seems to be better. But with many hills I have to go down two or more gears to even get it over the hill. The hills are not all that great. Have tried changing the Map Sensor, checking the hose connections around the TBI for vacuum leaks, all hoses for good connections and proper placement. When I remove the injector from the Throttle Body I found only one small O Ring at the bottom. (My manual shows two. One near the top of the body) I tried replacing it but still have same results. Any suggestions of something I might check and/or have missed? Is there any computer codes used on this model that might give me some clues as to the problem? One again thanks for all of your help. Don Smith

Reply to
Don Smith
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Your TBI has a pressure regulator inside it as well as more than one O-ring. You have an injector, a lower O-ring, a centering ring and an upper O-ring.

I would recommend a kit for the throttle body. This will give you at least the right parts for it and it gets a good clean while apart.

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's

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Reply to
Mike Romain

What comes in a kit for this Throttle Body Injector rebuild kit. The stores around here weem to want 75.00 for one and if it only has a couple of "O" rings I will be upset. Thanks Don

Reply to
Don Smith

It could have a new injector and maybe the regulator parts, I don't know for sure.

The kit for the 2 bbl carb is only $20.00 and that has all the gaskets, accelerator pump, float needle and seat, etc.

Have you changed the gas filter? That should be on the frame rail near the tank. A plugged one can also cause you top end issues, same for a dirty air filter.

There also is an air filter on the gas tank that will cause top end bogs if plugged up. That is a $2.00 emissions canister filter on the bottom of the charcoal canister. Running with the gas cap open or the tube off the canister so it sucks air tells fast if this is an issue but/and on some systems doing that can cause a check engine light to come on that will go off when you tighten the cap back on.

Mike

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Reply to
Mike Romain

Did you check on the basics? How is the compression of the engine? How is the tune and what do the plugs look like?

I had an '87 XJ with the 2.5 engine with the 4 speed manual transmission and it was slow. Even after a good tune up and a tight engine, it was still weak on power and just plain slow. It would get up to speed but if I was even towing an almost empty trailer it would slow down going up a slight incline. :-( I had to downshift to keep the engine in a good 'powerband'.

Of course your problem may be weak spark, too much or too little fuel, or a tired engine. :-( I sold my 87 XJ when I got my 88 XJ running. ;-)

good luck!

Reply to
dave AKA vwdoc1

Hi Dave Just went through and did a valve job and head shave to ensure it is not warped. New plugs, 160 lbs compression on all cylinders, good wires, etc. When I checked the Throttle Body Injection system I found that the large "O" ring was missing. I installed a teflon one around the injector body below the centering ring. ( Should it be above the ring???)

Getting ready to install a new fuel filter but do not expect that to help much. Starting to suspect something in the Injection system or its parts. Thanks again Don

Reply to
Don Smith

The fact that the TB is put together wrong means someone has already had the problems you are experiencing and has tried messing around. Running way too lean will burn out valves.

That gas filter might just be the ticket.

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's

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Reply to
Mike Romain

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