This is a problem that has been with my truck all through my upgrade program.

It seems that the truck idles great when it is cold but when it gets warmed up begins to have an idle that is unsteady.

It idles too low and sounds like it is going to stall.

Runs great off idle. Runs great cold or warm when above idle.

I have done a lot of maintenance and upgrades but this problems persists.
1. replaced all injectors
2. Replaced IDM
3. Had the PCM reflashed
4. Replaced the HPOP
5. Replaced CPS
6. Replaced FPR
7. Checked UVC harness and performed 50 cent mod

Anyhow, it is very irritating. None of my work seems to have made any difference.

 

Dose it do it with the ICP unpluged?

Chet

 

I havnt tried that but I did install a new ICP recently

 

Well new ICP should be alright if its OEM.

Chet

 

Let me bump this up to see if I can get some response.

The truck starts good, hot or cold.

The truck runs good with strong power once it is off idle, usually about 1K rpm

There seems to be a flat spot when you first press on the accelerator then it zooms off.

The idle is nice and steady when first started but becomes variable after the temp gage begins to come up.

When finally warmed up it idles like it is going to stall. Doesn't stall but gets down to 500 rpm with loud injector noise.

When it is warmed up and you put it in park it gets worse with the idle surging up to 1k rpm and then dropping down to 500 rpm. It will keep on doing that.

This is an E99 that has had a lot of recent upgrades ( new ICP, New CPS, new T-500 HPOP, replaced all injectors, new IPR, moded ICM, reflashed PCM, performed 50 cent mod, performed Hutch mod and Harpoon mod.and others).

This whole process started when my water in fuel light came on and I found water and dirt in my fuel bowl. I also unplugged the fuel bowl heater because it blew the fuse. The heater is still unplugged.

The idel problem started with the contaminated fuel bowl but has continued dispite the many repairs and mods.

Any comments would be welcome.

This problem predates the upgrades and is one of the reasons I started the upgrade program.

 

Boy, only thing I can say, did you clean out the fuel rails in case that dirt got by. I hope you droped the tank and clearned it and flushed the lines as well. Other then that I'm sure you checked all the electrical. Wires going to plugs etc.. Subcribing to this one.

Chet

 

I did drop the tank to check for contaminates. None found.

I did not clean out the fuel rails. Interesting thought.
However it runs so good when off idle that I have doubts that fuel rails could be the problem.

It seems to be something that occurs when the truck gets warmed up but only at idle.

Iam questioning some of the sensors. Such as the water temp sensor (we did change the water pump but reused the temp sensor), the MAP or the oil temp sensor. It seems something is giving poor signal after the truck warms up.

I need to do some research to see what sensor controlls the start and warm up cycle.

I am away from the truck for the next three weeks (work related) but will try changing out some of these sensors when I get home.

I also plan to have some programs loaded by DP to see if that cures the flat spot when first pressing the accelerator pedal.

I won't mind changing out the sensors as I want this truck to be reliable for the long term.

I will be looking for these sensors on E bay or at other outlets.

Duane

 

That is what I was thinking when I first read your post...Do you have access to AE? If so, start the truck cold and just monitor sensors to find if all of a sudden when warm, you get a bogus reading out of one of them.

 

Throttle Position Sensor, down by the gas pedal.
Check into a different CPS sensor or reinstall yours for possibly a better fit so the gap is more correct. Just a suggestion.

 

My cousin said he had fixed a couple of trucks with a problem similar to this. Said they would pretty much die when stoped at a light or sign. And like krazymaan suggested it was the throttle position sensor down by the pedal. Worth a look at least

 

I have suspected the Throttle Position Sensor ever since these problems started.

Trouble is, I can not see a connection between the temperature of the coolant and the TPS.

Same with Idle Verification Switch.

Still, if I can find replacements I will buy them. The dealer seems little expensive.

I do have and AE and will try using it. I havn't used it much yet and am a bit hesitent to try it out.

Will report results.

 

Does any one have the part number for the three wire throttle position sensor and idle verification switch for the early 99?

If I can get the correct p/n then I can search the web for the part.

 

Still hoping to get the part numbers so I can search the web for these parts.

Any one out there have a reliable source for parts?

 

Read this thread...ought to save you some bucks. Before I replaced my TPS, I'd remove it and clean the contacts with some compressed air and then a bit of DeOxit, followed by Faderlube. My turnsignal stalk gave me trouble about a year ago...a few drops of DeOxit fixed the problem and not a sign of trouble since.

Here is Horizon Ford and Tousley Ford.

 

I will try the contact cleaner when I get home.

Thanks for the response