90 F-150 erratic miss

[tillimon]

I have a 90 F150 with a 5.0 and when it is at operating temp, in any gear and at idle it has a erratic miss making it drop about 100 RPM about three months ago I did a tune up replacing the cap, rotor, O2 sensor, plugs, plug wires, coil. about a month after that the module on the side of the distributor went out and that was replaced it has been running great since then until about a week ago when this miss started I am at a loss any help please

 

[flareside_thunder]

Check your spark plug wire routing....2 and 4 and 7 and 8 can crossfire...also pull your IAC off and give it a good cleaning with carb cleaner and a wire brush.

 

[blacksnapon]

You might try using a squirt bottle with water. When its dark, spray water on the plug wires when its running. Any "leaks" will be visible.

 

[tillimon]

I checked all the plug wires and they were all good and no arcing. I can not do the IAC yet because lack of gasket availability. I decided to check the timing and when I removed the spout connector I noticed there is a little bit of corrosion and the base timing is at 10 adv. per ford spec. It runs fine without the spout in, I drove it around and when I returned home it was not doing it reinstalled the spout and it started missing again could it be the corrosion? I plan on cleaning it out for a temp fix (hopefully it will work) until I can track down a new connector and a plug.

 

[FordF-SuperDuty]

If I'm not mistaking there is no gasket for the iac.

 

[dustybumpers]

there's a gasket, but it usually is ok to use a couple of times, of coruse sinse I said that it will come apart. you have carbon in there, and have to take it apart and clean it. truck should quit when you un plug it

 

[tillimon]

Took the iac off and cleaned it same thing when and only when at operating temp it has a very fast miss and is erratic it will be anywhere from 5 sec. apart to 15 sec. apart

 

[flareside_thunder]

Clean the corrosion off the spout.....it'd be worth a try anyways.....

 

[dustybumpers]

change the 2 wire temp sending unit, it is giving the computer false info.

 

[flareside_thunder]

I don't know why it took me so long to say this...PULL CODES www.fordfuelinjection.com

 

[tillimon]

(to flareside) cleaned the spout and nothing. and it has a 31 I do not know which one it is my code book specifies for trucks but it is in the garage and I will be unable to look at it until morning

EVP - EVP signal is/was out of range - EVP

EVR - EVP signal is/was low - EVR

PFE - PFE signal is/was low - PFE

(to dusty) the coolant temp sensor?

 

[tillimon]

one thing I forgot to mention was the about 18k mi. ago I had the engine rebuilt and replaced all the sensors, egr, basically all the electronic components and valves connected to the engine so a lot of the stuff is new

 

[dustybumpers]

(to flareside) cleaned the spout and nothing. and it has a 31 I do not know which one it is my code book specifies for trucks but it is in the garage and I will be unable to look at it until morning

EVP - EVP signal is/was out of range - EVP

EVR - EVP signal is/was low - EVR

PFE - PFE signal is/was low - PFE

(to dusty) the coolant temp sensor?

coolant temp senser is the one near the thermostat. it has more than 1 wire. the temp sensor with 1 wire is for the guage, if the guage is working, that one is ok. I have had trouble with this senser in the past, it gives a false reading to the computer, wich changes from open loop/closed loop. and can effect fuel mixture, and timing. think of it as running with the choke on, on a carb'ed truck.

 

[flareside_thunder]

I could not find a list in any regulatory body where is it exactly? the only regulator that is displayed in the IP, but this is not what we want. until the cycle glow fuel pressure is up to 60 before you start even if you do not bleed, why does it matter, when it began in its specification.

Maybe I'm tired but this statement makes no sense...at least, not with lack of grammar.

 

[dustybumpers]

no, I just woke up, and I've got nothing........

 

[tillimon]

The code that showed up was a old one that was stored in the tester and was showing up during the test I cleared the tester and checked it again and no codes showed up. I will try a new temp sensor I am running out of ideas

 

[tillimon]

Replaced the coolant sensor and nothing. What should it be idling at when it gets to temp the idle is around 600 I think it used to be higher before the issue started.

 

[SEMPERFIDELUS8403]

I have the same problem with my 90 F150 5.0... I am changing the fuel filter out this week, hopefully that will at least eliminate one possibility