Renix running rich - need help

Hey guys,
Had the 2.5L rebuilt this summer, and got it buttoned up in September. I replaced all the sensors except for the TPS (original?) and 02 sensor, which was 3-4 years old.

Here in NJ, my MJ would have never passed the free state inspection (hole in floor, non-op e-brake, no fender flares covering 31"s. In time, that stuff will all be done. In the meantime, I need the sticker, so I took it to a shop that does inspections and they overlook most of that stuff. But not emissions. I had high hydrocarbons and CO%. The tech said "that's usually the 02 sensor," so I returned mine under warantee, and got another Standard Ignition 02 sensor. Bring the truck back and the numbers are even higher!

It runs/drives OK, certainly not smoking, but rich smelling when it's cold (which I would expect). It needs to have the TPS replaced (which I'm doing this weekend). With all new sensors, what could cause this? My buddy has an MT-2500 which he's bringing over to help me with the TPS adjustment -- will that tell the story??

If it helps, me and the engine builder were concerned about a little excessive oil consumption at 700 miles. He was surprised to hear that the CCV system has no PCV valve and wondered if I have adequate crankcase ventilation. I'm going to check vacuum on the oil dipstick this weekend too -- could it be related?

Hatin' Renix right now.
Thanks!

Tom
87 MJ 2.5L ax5 4x4 4.11s

dont know much about the 2.5, but is the engine getting up to the correct operating temp? is is getting into closed loop?

As long as you buddy has the Jeep cartridge for the MT-2500 you will be able to read real time data. I have the same scanner, it works great. I wouldn't trust the "Standard" brand O2 sensors at all. I have always had bad luck with them. I have had really good luck with Bosch O2 sensors though, or get a Delphi/GM brand as in the Renix years that's what most of the sensors are.

I haven't dealt with those motors really at all,but if there similar to the 4.0 then then the cps controls timing and spark which could make it run rich if the timing is not correct...as for the oil are you having any leaks around the valve cover or the filler cap?

It has to be up to temperature to for the Renix to enter the closed loop mode. Check the temperature of your upper radiator hose with an infared gun to see what the temp is. If the vehicle is at the right temperature (not sure what the "right" temp is on the 2.5...), then check the coolant temperature sensor. Its cheap enough to just replace, as a matter of fact, rather then checking it.

It does seem to be running cooler than usual (per the stock gauge). I put an aluminum radiator in it with the rebuild, and an electrical fan, which really almost never comes on as long as I'm moving. The inspection guys have a fan they blow through the grille to keep it cool on the dyno, but I know they warmed it up so that it wouldn't be (ideally) in open loop. It has a stock 195* stat in it, and a brand new coolant temp sensor (which was NOT easy to find). If it's running too cool, but warm enough for good heat, where do I go from there?

As for products, one mechanic told me Standard was good and Bosch was junk -- who knows? My old one was Bosch, the new one is Standard, both apparently work, neither is the problem. And no, I have no leaks at all and no blow-by, which was SIGNIFICANT on the original, worn out engine.

My gut feeling is that it is getting out of open loop. When I start it on a cold morning (27* today), it is rough and SMELLS rich out the exhaust pipe. In a few minutes, the idle smooths out and it drives pretty nicely.

My RENIX with its super efficient closed system runs too cool even in the summer. I block the grill completely off in the fall, winter and spring to keep it in closed loop.

Tell them to cut the fans off and try it again. Or block off your grill so they can't blow cold air by it.

Did you clean or replace the injectors with the rebuild? You may want to run some Lucas FI cleaner and upper cylinder cleaner through it for a tank full and see if that helps.

OK here's some results from the DRBII this afternoon. My friend is a Ford-certified ASE mechanic, but had access to this scanner and the Chrysler module. Much more data than I thought. We ran a "test" which instructed you to turn the key on, start the car, accelerate to 1500rpm, then turn it off. We got fault code 409, and had no clue what that was.

Anyway, he could smell how rich I'm running, and wondered if my new fuel pump was delivering too much fuel. The data showed that I wasn't coming out of open loop. I was hitting operating temperature and the coolant temperature sensor was operating, the MAP sensor was reading properly, we adjusted the TPS, and it would not come out of open loop.

Anyone know what fault code 409 is? Anyone know if a rich-running mixture can CAUSE Renix to stay in open loop, or is it the other way around?

The only Renix issue that was maybe going on is we switched around my current (new) O2 sensor and a used one lying around. Both didn't fluctuate much : one stayed around 0.9 volts and the other around 0.4 - 0.5. Again, cause or effect?

We even swapped in an extra fuel injector, just to make sure it wasn't leaking/causing a rich condition.

Thoughts? I guess check fuel pressure next.

Does the temp sensor work Ok because it could lead to the ECU thinking it was hot enough when it was actually cool. The other thing to check is the heater on the O2 sensor. It may be not getting the full 13 volts it needs to operate at it's most efficent.

The DRB was giving us real time coolant temps from the coolant temp sensor, and they were in line with the gauge, so yeah, it was getting in the right temp range. I know a brand new 02 sensor could still be bad, but it seems to heat up and start giving readings 30 seconds or so after startup. Plus, we popped in a spare 02 sensor that did the same thing! I will check to see if the sensor is getting 13v with key on, though; thanks. It really started running rich after the fuel pump was replaced, but that was right after the engine and all sensors were replaced, so theres a few variables.

Is the fuel regulator functioning correctly then?

I don't believe (in fact I'm pretty sure) the 2.5 doesn't have a fuel regulator. Does it??

it does, possibly in the TBI??
http://www.autozone.com/R,2114361/v...partType,00165/shopping/partProductDetail.htm

Huh, well hell, yes, it does. I need to make sure I'm getting 14.5PSI at the TBI. Anyone recommend a fuel pressure test kit to buy or rent that is easy and accurate?

Check out the manifold air charge temp sensor to the rear of the TB on the manifold. People overlook this one. You can check it with a voltmeter

Tom - did that - it's brand new and operating properly.