Stig01

Ok guys, I am at the end of my rope and need some advise from someone more experienced with these cars. First, my current motor related mods are as follows:

BBK Shorty Headers with high flow cats and true duals
K&N filter
High CFM Fan with independent Relay

Now on to my issues. In the morning when I first start the car, it will not idle. It will die unless I rev it until it starts to warm up, and then idle's like its got a massive cam. Once driving, the idle will hang as high as 2k until i come to a complete stop. It will also backfire and miss under load.

When the car is warm the in the afternoon the idle is better but still rough, backfire is less often but still there.

I replaced the Idle air control valve last night thinking this was the issue, but no dice. My Mass air sensor is less than a year old, and I did find and fix a vacuum leak several weeks ago.

I should also note that I have had an issue with my headers burning plug wires and causing a miss under load but have inspected all of my wires and they appear to be fine.

Any help would be greatly appreciated, I love this car and would love to be able to drive it to its potential.

dawson1112

TPS can cause all kinds of issues , have you tested it ?

http://easyautodiagnostics.com/ford_...tps_test_2.php

dawson1112

also a test of the ect should be performed.

http://oldfuelinjection.com/?p=28

Before you start the car note the ambient temps surrounding the engine using a thermometer. This will give you a pretty good idea of what you coolant temp is cold before starting. using the chart in the link take a reading of your ect . say if the ambient temp is 75 you should get a ohm reading of between 24.27k-37.30k +/- 15%

Or a voltage reading depending on how you test. Of between 2.62v-3.06v
]
If the ambient temp of your cold engine is 75 any your getting a reading showing much colder then it is reporting to the ecu a false temp.
A lot of times the ect will report a temp of -40 degrees and this will cause the ecu to widen the pulse of the injectors dumping so much fuel that the engine struggle to stay alive.

A false reading of too hot will have the opposite effect causeing a very lean condition and you may get popping and back firing.

Some times the ect when cold will report a very cold reading then as it warms up it will report a very high reading.

An egr valve that is stuck open can cause the engine to stumble at idle also.

Stig01

Thanks for the advise guys, I did forget to mention that the ect is only a few months old. I will test the TPS Sunday when I am off and see what the results are.

Stig01

Well Ive been busy with the car this morning. TPS tested fine, voltage seems to be in line with no odd readings at any position. Also tested the new ect, and also tested fine.

I cleaned and tested my MAF, and it seems to be operating as it should, except when the the idle is slow to return, the voltage from the MAF follows the same slow return pattern. Could the MAF be causing my idle issues?? If so, why would I have gone threw two MAF sensors in 12 months?

dawson1112

What kind of air cleaner do you have ?

Some times the reusable ones that have oil in them can cause trouble with a maf if there is to much oil in the filter.

Stig01

Forgot to add, I did check the codes this morning as well.

I had codes for the tps (which I unplugged earlier this week and I am sure caused this code) a code for the MAF and a code for the right o2 being lean.

Stig01

I have a k&n filter, however I have not oiled it in a long time. I have heard many people say they can cause issues with mass air cars, however k&n says this is not possible....

I did clean the MAF as I said, and it did not appear dirty. I did look at my receipt and the MAF on the car now is a re-manufactured piece. could just be a low quality MAF I guess...