[ZeeJay1997]

Could a partially clogged exhaust mimic an intake leak?

[ZeeJay1997]

Is it just my Jeep or are do all factory tailpipes have a deep flat spot where it clears the sway bar?

I disconnected the o2 sensors and it runs better, but still starts missing above 3k.

[ratmonkey]

Timing is variable and depends upon several inputs.

I'm not liking the way that map is performing. They do go bad. But that's probably stuttering because if the detonation.

I can't remember, how's your fuel pressure? Can you run a gauge off it while you're testing that hill?

What percent is the tps actually reading at wot? Voltage?

[ZeeJay1997]

I drove it 75 miles this morning. Performance is markedly increased with the manifold change. Also late yest, I drilled 3 half inch holes in front of the stock muffler. I also moved the TV one notch toward the firewall.

Now that I have the manifolds squared away and I'm driving it normally instead of like I stole it, when the engine is under moderate load, the brake booster starts hissing and gets louder with load. Figured out it's pulling air in at the fitting under load, so some black RTV is drying now.

To answer your question about the TPS, it's a new BWD and I can only get about 3.8 volts out of it at WOT and idle wouldnt come in either, i forget what it was. All sensor inputs are 5.08v across the connectors. The one I replaced read the same thing. I reckon it's time to go see mr mopar.

My fuel gauge hose is too short and i didnt have time to dig thru all my adapters and hoses to make something up. Under no load and 2500 it holds 50.

I checked the MAP with a mity vac and meter and couldnt find anything wrong. The PCM output to scanner and vac gauge match on the road.

So, it's more drivable now, but still sucking at hard accel. Gotta do a mopar tps, cat back, and keep an eye on the brake booster vac inlet. The lie-ometer said 20.5 MPG average on the trip in and I didnt get ran over poking up hills.

I'm not going to try to judge the transmission until I get my engine "properly tuned"

Thanks for any input.

[ZeeJay1997]

Oh, yeah, yest when I was driving it like I stole it, I ran a data report and the temp was up to 220 at one time when i was cycling the throttle to max check the fuel loop. Also when i drilled those holes a lot of pressure was escaping and the flat spot on the tailpipe is white.

That's why I say think my exhaust is restricted. If I keep screwing with this thing, I may eventually get ti fixed.

[JS97ZJ]

I think your almost home on this one. Getting there has been a job. i'd get that vacuum up to at least 18 (20 better). If you isolate the booster does the vacuum get better?
If my understanding is correct, the map and TPS will setup fuel trims and timing. If the PCM has a borderline starting point, top end performance would probably be effected.

[ZeeJay1997]

Originally Posted by JS97ZJ

I think your almost home on this one. Getting there has been a job. i'd get that vacuum up to at least 18 (20 better). If you isolate the booster does the vacuum get better?
If my understanding is correct, the map and TPS will setup fuel trims and timing. If the PCM has a borderline starting point, top end performance would probably be effected.

Yes, I clamped off the booster hose and still only get 15 PSI. I sprayed ether on the manifold gasket with no reaction from engine. At 2000 RPM no load I get 19 PSI. I saw somewhere that a test for exhaust restriction is to hold it at 2500 no load for 3 minutes and watch for it to start losing vacuum due to exhaust backup. I tried that at 2000 and didnt decrease PSI. One other thing I noticed is that it is running rich at idle... stinky.

Has all new secondary ignition and coil is per spec resistance. When I pull the plugs they are clean.

I dont think MAP and TPS will affect manifold vacuum at idle... unless they are causing the PCM to retard the timing... It's idling at about 770.

[JS97ZJ]

What I meant to say was you have great compression and shouldn't have the low vacuum. That's where the theory of operations comes in.
If the PCM is screwing around with the fuel trim because the map sensor is sensing a lower vacuum, would it not make sense that the engine's performance be affected when you got into the higher rpm's. ????
Just trying to hang in on this one...

[ZeeJay1997]

Originally Posted by JS97ZJ

you have great compression and shouldn't have the low vacuum.

Yeah, I'm puzzled about that too.

Originally Posted by JS97ZJ

If the PCM is screwing around with the fuel trim because the map sensor is sensing a lower vacuum, would it not make sense that the engine's performance be affected when you got into the higher rpm's. ????

It's the MAP that came from the factory. You, RM, and me all suspect it, but I can't find anything wrong with it. Maybe I'll change just for grins.

I know the TPS voltage is not to spec. Cant get closed throttle voltage low enough. Scanner is reporting 18 degrees open. Allpar says it should be 10. I used a spare and elongating the mounting holes and using washers to adjust, but I still couldn't get the voltage range right from idle to WOT. The range is just not there. It's been this way for years (checked it when the PCM started acting up) and I've never had the symptoms I'm having now.

Then I have the rise in temp when the high end bogging starts...

Thanks for your help, keep throwing those ideas out. Something may fix it without taking the head off.

[torchd]

Originally Posted by ZeeJay1997

I just had the TB off and cleaned it. All is good there.

Just took it out and checked witrh scanner again. The PCM is not opening the fuel loop when at WOT or accel. It's starving for gas, not air. Going to put my old stalling PCM back on it and see if it does the same thing.

Sorry to get off topic here. When you pulled the whole TB off from the intake, how do you remove all the cables connecting to the TB arm/mount?

BTW try to adjsut your throttle cable that is located on the TB arm/mount

http://www.jeepforum.com/forum/f13/h...97-zj-1356598/

[ZeeJay1997]

Originally Posted by torchd

Sorry to get off topic here. When you pulled the whole TB off from the intake, how do you remove all the cables connecting to the TB arm/mount?

BTW try to adjsut your throttle cable that is located on the TB arm/mount

The two forward one snap off by pulling toward left fender, The one closest to the TB snaps off by moving it toward TB.

TV cable is adjusted correctly.

[ZeeJay1997]

I've been easing around in this thing since my last post and driven about 500 miles. Checked the oil yesterday and is thin, smells like fuel, and about a pint over full. Still craps out about 3200RPM and starts slight missing with rich o2 readings and a little smoke. All signs of flooding. Also it was 90 in north AL yest and the eng temp was running about 10* high with AC on over 60.

Is it possible/probable that the compression chamber doesnt have enough o2 to burn the fuel the PCM is throwing at it? Maybe due to clogged exhaust? I'm leaning towards getting it replaced.

Thanks for any ideas you may have.

BTW, I did replace the TPS

[JS97ZJ]

Injectors gone bad?
That's a lot of fuel in the oil. If you still have your original injectors, try putting them back in, then do a disco. Some one else also had problems running rich with the 703's. It seems to running good for a long while then it comes up with this running rich symptom. He removed then and went back to his originals
Also your cat isn't that old...?????

[DougE]

Old school thoughts. Lost of power going up hill or accelerating on flat at highway speeds to pass usually indicates a blocked fuel filter. With that much mileage it could also mean the fuel pump is going.

[Uniblurb]

Since just throwing out ideas here I changed my air filter and believe it was blocking enough air going through the intake. It didn't look hardly dirty at all, I had blown the dust/heavy pollen out of it several times before, and just slightly discolored yellow/brown. Changing it out made my ZJ run so much better and don't know if it's just a coincidence or not. I know, it sounds like way too simple of a fix.