I all of a sudden have a very rough idle, feels like a I have a big cam. In park and drive you can't feel it to bad but when it is in gear it is really rough. It is a Mustang shortblock, GT-40 alum. heads, all the stock 87 F-150 intakes upper and lower, rebuilt injectors, new plugs wires, new C-6 tranny, Bassani headers and Y-pipe, stock ignition and fuel system, mass air conversion from Ford Motor Sport, all emissions parts are still there, stock air box, intake to the air box from a 6 cyl., new battery.

It has run perfect for for almost a year now, there doesn't seem to be any loss of performance. I bought a code reader and pulled the codes tonight, the manual I have doesn't really help me to solve anything. The book that came with the code reader gives me this information:
KOEO codes
85 - Canister purge circuit
95 - Fuel pump secondary circuit
Continuos codes
14 - Ignition profile pickup (PIP) circuit fail
33 - EGR valve fault not closing properly
95 - Fuel pump secondary circuit fault

Any help would be great or any websites that talk about solving these problems. The only thing I can find on the net is the same thing the book tells me about the codes. I pulled the codes with an Iequus code reader, it has an liquid crystal display and shows the codes so you don't have to pay to much attention and try to count light flashes or beeps. Much better than using a meter or the CE light and counting.

 

You need KOER codes.

 

I meant to type, in my first post, the idle is really rough when stopped and in gear. P and N at an idle aren't to bad. Normal driving and WOT seem fine.

The first line of the KOER test states: The KOEO must be performed first, and a "pass code" must be obtained before performing the KOER self test: otherwise, results of the KOER self test may be invalid.

Ignition timing and timing advance must be operating properly in order for the KOER self test results to be considered valid. Perform ignition timing check before performing the KOER self test.

I will perform the other test after I check the timing, timing advance and get some information about correcting the first set of codes.

 

I would focus mainly on the PIP code. It is directly related to ignition, and the problem may be more noticable at idle in gear. I think that the canister purge code and the fuel pump code are simply due to the wires not being hooked up on the truck. They shouldn't cause any driveability problems as far as I know. The mustang computer (I assume that's what's in the maf conversion) monitors the power side of the fuel pump relay to make sure that it is working. The truck computer didn't monitor this, so there is likely no wire run for this. The truck also didn't use a canister purge valve, so likewise, the wiring and the valve are not present, which throws the code. I'd go ahead and try to get the KOER codes and see what comes up. If the problem is constant, it should show up in the engine running test too.

 

Thanks for the information, I will try the other test today and see what I get.

 

The continuous code 33 may be a clue, the EGR valve may be open at idle and could cause a very rough idle. Run the KOER.

 

I ran the tests again, here is everything one more time. I also noticed while looking at the codes there is a (cars only) (Trucks only) next to some of them. I noted that next to the code this time.

KOER
94 - Air diverter solenoid circuit fault (cars only)
44 -Thermactor air system fault
33 - EGR valve fault/not closing properly

KOEO codes
85 - Canister purge circuit (Trucks only)
95 - Fuel pump secondary circuit
Continuos codes
14 - Ignition profile pickup (PIP) circuit fail
33 - EGR valve fault not closing properly
95 - Fuel pump secondary circuit fault

 

If you have a vacuum pump, it's an easy thing to check and/or eliminate the potential EGR problem. While the truck is running, apply vacuum to the EGR valve, which should make it open, and also make the idle drop. You should also be able to see the diaphragm in the EGR valve move up in down. When you did the rebuild, did you reuse it, or buy a new EGR?

 

I had just changed the EGR a few months before pulling the engine and installing the new one so I did not replace it. I got the EGR codes with the speed density system from day one of owning the truck. I bought the truck new with 2 miles on it. I replaced it a couple of times on the old setup over the years, when the gas mileage got real bad I would replace it. I never noticed any difference in the way it ran when it was not working before though. I have a 91 Mustang also, the EGR was out on it and the car ran fine, just bad MPG's.

I removed the TIF module today and it was fine. I compared it with 2 others I had and they all had the same readings within specs, I replaced it just because I had to pull the distributor to get it off. I also checked the PCV valve, it was fine, replaced the fuel filter just for fun. Vac. readings are around 17 at idle and 20 at high idle. I played with the timing and that didn't seem to do anything either.

I never checked the codes after I put the new engine in, pretty stupid because it may have had all these codes all along and been running just fine. I also never sat down to see what codes I might get with the computer change. I am going to check the resistance of all my spark plug wires tonight and maybe change the plugs just for fun.

I am still open for suggestions.

 

I checked all my spark plugs and wires and everything checked out fine. I installed a set of new plugs but after a year the old plugs looked perfect. I thought it was fixed at first but it is still does it after driving around today. The idle is dropping down to 500 RPM if you sit long enough with the brake on and the truck in gear when it is warm.

 

I unplugged the vac. lines to the brake booster and EGR then plugged them. It still does the same thing. I unplugged the IAB electrical connection and the idle really drops, I create a vac. leak and the idle really drops. I guess the next step is to check the fuel pressure?

 

Clear the codes and see what new ones you get.

 

I ordered a new EGR solenoid, the one located by the coil bracket that sits above the drivers side valve cover. I took it apart after reading another post that talked about how it had a filter that could be cleaned and the rubber valve could also be cleaned. I also thought this could be the only other thing throwing the EGR not closing code since the EGR is fine and the EGR sensor tests fine and seems to be woking. My intake is still clean on the inside after almost a year on the road, no black carbon or anything, looks like it did when I took it out of the hot tank. The filter fell to bits when I touched it so I just ordered a new one, I got one from the junk yard to put on till the new one comes in. I cleared the codes and it ran fine for a 1/2 hour or so and then the rough idle came back. I think it may be the thermactor air valve, I couldn't find any in the junk yard and Ford wants 140 bucks for a new one. Next I plan to take it off and test it and see if my air pump is pumping also.

 

The new EGR solenoid must have fixed the EGR codes. I am getting better gas mileage now also, the EGR codes are gone. The PIP circuit code is also gone, I think this is because the CE light is back in the circuit and it is passing the PIP circuit test again.

I have started to work on this problem with the Ford tech hotline also. I installed my CE light, it was in the truck for a few days after I bought it new and the shop removed it. I never put it back in after I did all this work. The CE light is not coming on while driving. When I turn my key on, the instrument lights light up the battery symbol and the Engine symbol, when I start it they both go off. I don't know if the CE light is supposed to come on also? I tested the bulbs in the blinker location to make sure they worked. My friends speed density 91 truck turns on the battery light and the CE light when he turns his key on and then they turn off when he starts it, all his lights are in the same location as mine also, left blinker light, CE light, Engine light, battery light. No lights come on while I am driving.

I ran through setting the idle tonight using a document the tech line sent me, warmed up the engine, unplugged IAB and set the throttle screw to give me a nice idle, measured the voltage at the TPS, it was around .7v, I adjusted that to .96v, removed the - battery cables for a 1/2 hour, plugged the IAB connector back in, reconnected the battery and started the engine up. It idles about 750 RPM but still feels a little rough and still rough when in gear with the brake applied, maybe not quite as bad as before. I will give them another call and keep troubleshooting. It has to be something obvious.

 

The problem turned out to be the lower intake manifold was not sealing to the new Y303 heads. I purchased the Edelbrock truck manifold upper and lower, installed it and the problem is gone. You could see on the gaskets where it was leaking with the old parts. I have been driving for a couple months now with no troubles.