AK to HI engine code every new part gets worse

[SBpunk]

Has anyone considered fuel starvation from a potentially plugged fuel filter?

Fuel filter is in the tank right? Definitely sounds possible. Would it cause it to throw codes?

 

[peuglow]

Not sure. Never did with mine. Did you get your code reader yet?

 

[SBpunk]

Sure did... getting a P0123 code (this one is new) and multiple misfire P0301 P0300P and P03004P

 

[xeroOTG]

Let me whip out my FSM and get the exact reason in a bit. The fuel filter is on the frame rail, just follow the fuel line from the tank. Basically low fuel volume leads to starvation at some point in the power band. This causes misses, lean conditions, and bad vacuum. There is no sensor that reports fuel pressure so the system assumes fuel flow is constant and only reports the symptoms and not the cause. The reason your vehicle is running worse as you add parts is you are changing the operating variables, and therefore the system is not able to compensate. The fuel table is based off of a set of known parameters, and variables. One is throttle, another vacuum, and intake air. When you change all three variables to an unknown uncompensated value there is no way of allowing for error on known constants (fuel pressure).

 

[xeroOTG]

With those codes I would look into a coil. The tps high volt condition could be from the system not adjusting its parameters in limp mode and expecting the old tps configuration. I would definitely look at a coil and fuel filter, they are inexpensive, and reset the ecu while you are at it.

 

[SBpunk]

Coil was changed. I haven't messed with the coil pack. The black bar on top of the fuel rail area. Me and a buddy searched for an inline fuel filter but no luck. There is a metal box the fuel lines run into just before the rear driver side tire.

 

[Ecomike]

http://www.obd-codes.com/p0123

What does that mean?

A P0123 code means that the the car's computer has detected that the TPS (throttle position sensor) is reporting too high a voltage.
Symptoms

Symptoms may include:

• Rough idle
• High idle
• Surging
• other symptoms may also be present

Causes

A code P0123 may mean that one or more of the following has happened:

• TPS not mounted securely
• TPS circuit short to ground or another wire
• Faulty TPS
• Damaged computer (PCM)

Possible Solutions

If there are no symptoms, the simplest thing to do is to reset the code and see if it comes back.
If there are symptoms such as the engine is stumbling or hesitating, carefully inspect all wiring and connectors that lead to the TPS. More than likely the problem is with the TPS wiring. Check the voltage at the TPS (refer to a service manual for your vehicle for this specific information). If the voltage spikes or is too high (over 4.65 volts with key on, engine off), then that is indicative of a problem. Carefully trace each wire from the TPS wiring harness to check for breaks, rubbing against other components, etc.

 

[SBpunk]

http://www.obd-codes.com/p0123

Man ill be a little upset since I just replaced the sensor. Ill google how to test it and report back. Thanks everyone.

 

[xeroOTG]

Coil was changed. I haven't messed with the coil pack. The black bar on top of the fuel rail area. Me and a buddy searched for an inline fuel filter but no luck. There is a metal box the fuel lines run into just before the rear driver side tire.

That's related to the emissions system, I guess they moved it on the 98's, I just looked at mine. The only xj I ever did a fuel filter on was a 92. Back to the FSM...

The fuel filter apparently is part of the pressure regulator on top of the fuel pump.

 

[Ecomike]

Man ill be a little upset since I just replaced the sensor. Ill google how to test it and report back. Thanks everyone.

I have read a lot posts about bad CPS and some TPS sensors off the shelf lately, all aftermarket stuff from China. But it could be wring, a short in the harness. It is not uncommon for the front drive shaft or exhaust manifold to damage loose sensor wiring.....

You should have a 5 volt input from the PCM to the TPS, a ground, and a return signal from the TPS to the ECU.

And if you still have the 30# injectors in there that must be a big part of the problem too. Fuel pressure drop at WOT possibly, as they let too much fuel flow, poor atomization, then too much fuel at cruise and idle.

 

[SBpunk]

Ok tested the TPS and it was coming up .931 on the 2k OHMs

 

[SBpunk]

I have read a lot posts about bad CPS and some TPS sensors off the shelf lately, all aftermarket stuff from China. But it could be wring, a short in the harness. It is not uncommon for the front drive shaft or exhaust manifold to damage loose sensor wiring.....

You should have a 5 volt input from the PCM to the TPS, a ground, and a return signal from the TPS to the ECU.

And if you still have the 30# injectors in there that must be a big part of the problem too. Fuel pressure drop at WOT possibly, as they let too much fuel flow, poor atomization, then too much fuel at cruise and idle.

I ordered those injectors before I was home so its possible they are way too much. Hopefully the new injectors will be on tomorrow.

 

[xeroOTG]

Ok tested the TPS and it was coming up .931 on the 2k OHMs

You could also check your old tps if you still have it. Tps's are... problematic. I really like your explanation ecomike. I guess I looked over that part of the thread. Either wat sbpunk good luck.

I have read a lot posts about bad CPS and some TPS sensors off the shelf lately, all aftermarket stuff from China. But it could be wring, a short in the harness. It is not uncommon for the front drive shaft or exhaust manifold to damage loose sensor wiring.....

You should have a 5 volt input from the PCM to the TPS, a ground, and a return signal from the TPS to the ECU.

And if you still have the 30# injectors in there that must be a big part of the problem too. Fuel pressure drop at WOT possibly, as they let too much fuel flow, poor atomization, then too much fuel at cruise and idle.

 

[SBpunk]

Thanks for the diagram xero... I'll call around tomorrow and see if I can find a part local. Would be nice if it was just the fuel filter and injectors. The tank was empty when I picked it up at the port and I ran out of gas trying to get out of the parking lot (idiots couldnt even leave me 1/4 tank). Probably sucked up all the nasty shit into the filter.

 

[Ecomike]

I ordered those injectors before I was home so its possible they are way too much. Hopefully the new injectors will be on tomorrow.

I know they are way too much. Two other posters here recently pulled their hair out trying debug problems and their problem was trying to use about 24-26 lb injectors and they had crazy issues that were solved by going back to stock flow rates.

 

[xeroOTG]

I know they are way too much. Two other posters here recently pulled their hair out trying debug problems and their problem was trying to use about 24-26 lb injectors and they had crazy issues that were solved by going back to stock flow rates.

Definitely explains the backfiring and the misfires. Guess i was close by guessing fuel... just wrong side of the spectrum. Would it maybe a good idea to try the injectors first, then the filter? It looks like it might be hard to do that filter but i don't have experience with it so i cant say...

 

[SBpunk]

Definitely explains the backfiring and the misfires. Guess i was close by guessing fuel... just wrong side of the spectrum. Would it maybe a good idea to try the injectors first, then the filter? It looks like it might be hard to do that filter but i don't have experience with it so i cant say...

Its not hard just a pain in the ass. Least it was on a CJ7... rusted bolts and what not. If the injectors don't help fuel filter will be next. It probably needs changed anyway. I picked up these http://www.precisionautoinjectors.com/product.sc?productId=11 awhile back just waiting for them to arrive. Hopefully they are 19lb. If not I'll be grabbing some ford #19

 

[peuglow]

Thanks for the diagram xero... I'll call around tomorrow and see if I can find a part local. Would be nice if it was just the fuel filter and injectors. The tank was empty when I picked it up at the port and I ran out of gas trying to get out of the parking lot (idiots couldnt even leave me 1/4 tank). Probably sucked up all the nasty shit into the filter.

Don't the tanks draw from the bottom anyway? I don't think running a tank dry would necessarily draw more crap into the filter, as they are always drawing from the ''crap lined' bottom of the tank.

 

[Ecomike]

Don't the tanks draw from the bottom anyway? I don't think running a tank dry would necessarily draw more crap into the filter, as they are always drawing from the ''crap lined' bottom of the tank.

It does if the crap was floating.

 

[peuglow]

It does if the crap was floating.

Have you ever come across a tank that had floating crap in it?