Gentlemen,

After replacing fuel injectors AIR rail and some gaskets, I have triggered some CEL Codes on my 1995 4.9L.

Fuel Trim (173)
MAP (129)
TPS (167)
Knock Sensor (225)

KOEO 111 initially but 173 in the continuous memory. KOER I get all 4 codes. I know some of these are usually due to operator error but I cannot pass after a number of attempts and I have done this successfully before. The MAP sensor and the TPS sensor were both tested and within specs. Fuel pressure 55 psi (normal). Manifold Vacuum steady at 21 Hg. All new vacuum lines. Spark plugs look O.K. to my untrained eye. Idle at normal RPM's.

Perhaps I must fix the continuous memory code before attempting the KOER? I am however experiencing these symptoms.

1) low on power
2) needs lots of gas to get moving from stoped
3) occasional whistle in 1st and 2nd gear
4) exhaust smell near cab

My assumption is vacuum or exhaust issue but so far I have come up empty with the search. One additional thing, after reseting the computer she initially drove fairly well, idled higher perphaps, but I only needed to depress the clutch to get moving. Then she settled down into her regular ways (described above).

 

possibly something left unplugged? how is it for power when its still cool? before it up to operating temp

was it running ruff before you did the work to it?

 

Rustee...

She was running poor before, bad leaky injectors. Misfires, stumbles, etc. She has always need lots of gas to get moving and seems to hesitate when doing a snap throttle under the hood. But she wasn't setting any codes before the recent repairs. Almost like the leaky injectors were keeping the idle mixture closer to ideal?

 

What do you have for an air filter. Is it clean, if it's a K&N is there to much oil on it. How about your cat. Is it old or trying to plug up? Usually when you over fuel the cat will start deteriorating and start breaking down either plugging itself or the muffler.

 

crewcabber,

stock air setup newish filter. I don't the history of the cat before purchasing the truck last year. Can't imagine the leaking injectors were very good for it though. She has dual cats, so its probably stock? New looking muffler. No rattle or anything when banging on the cats. I suspect that shes running lean now? Code 173 fuel trim rich, means the computer has reached its limit in adding fuel?

 

Just a few questions for you...

How did you check the MAP and TPS sensor?

What is you "Base" timing at?

Have you verified all vacuum lines are properly connected?

Are the vacuum lines vinyl or have you replaced the vinyl vacuum lines with new rubber lines?

It sounds like your timing isn't advancing, which the PCM controls.
Another possibility is- Failing or failed PCM. What is the reference voltage for either the TPS or MAP sensor? If it's above 5 volts, that would perhaps point to failing capacitors in the PCM.

I'm just giving ideas here and some are firsthand experience. Let us know what you find.

 

timbersteel, thanks for the suggestions...

I will look into timing issues. Running 10 degrees btdc. All new silicone vac lines. Tested for voltage, ground and function on MAP and TPS. I recently inspected the computer circuitry and it all looked good.

It takes awhile for the CEL to come on. I want to say that since fuel pressure and manifold vacuum appear normal this is an air issue. But perhaps a faulty temperature sensor?

 

And another thing, oil pressure has increased slightly. It has always read high but now even more

 

These two things suggest an exhaust leak near the motor which will cause an uncontrollable lean condition, double check all air injection hoses and valves for cracks as these are also connected to the exhaust.

 

Conanski, Thanks, I will check that out. I was looking at so many variables It was hard to see the big picture.

 

if you had leaky injectors and had them for a while its possible all the unburnt fuel may have plugged your cats which will definatly make it feel low on power slow to accel you could drop your exhaust at the manifold and drive it ( fire exstinguisher handy ) or get ahold of a 02 back pressure tester mine was 50 bucks from matco tools one very good investment lol

you could also have a trans problem not starting off in first or torque converter slippage



but i would check the air system first at conaski said

 

Update... I was playing around this afternoon. Disconected the O2 and plugged the evap system at the throttle body. No dramatic change. So I disconected and pluged the EGR. Automatic difference in the way she drives. EGR is new, suspect solenoid? I'm gonna keep it up and see what I can find.

 

Brethren,

I don't know what to say, problems continue. Now I am getting a Lean code (172) along with the others. May have sprung an oil leak and what I thought was a small exhaust leak now sounds like a large one. Disconecting IAC results in no RPM change. When I unplugged the 02 and the EGR why would I set a code for EGR but not 02? Bad 02 ground?

 

damn y'all this is killing me - new 02 sensor in the mail... hoping this is a cheap cure

 

You said u disconected the iac. And it didnt change. Well il pretty sure it should have died when u did thAt U have replaced the vacuum lines. Check the throttlebody and make sure the plates are closing all the way. Or your iac could be stuck open.

Pull the vacuum line off the egr valve and plug it Use a vacuum gun and manually pull on the egr valve then release the vacuum and make sure the valve is closing all the way. May have to take it off to do that



Did u find where the exhaust leak is. That could cause alota troubles