Flashthompson

New to the Forum. I have a 95 F150. Last weekend my truck started running rough when I would press on the gas slightly to accelerate to maintain speed. truck would shake until it downshifted. Checked the codes and it threw a code that the EGR had insufficient flow. Changed the EGR, the sensor on top and the vac line. that fixed the code. But its still running rough with a high idle. Somewhere around 1100 to 1300. Itll drop then rise again. Cleaned the Idle air control valve, still didnt fix it. Tomorrow I was going to change the throttle position switch. Any ideas if that doesnt work?

raski

Bet you have vacuum leak somewhere. I had a throttle body bind up causing your symptoms too. Did it idle fast prior to changing EGR?

Flashthompson

I dont remember. I think so but i was more focused on the check engine light and what that meant along with no power and strong exhaust. So when I ran the codes it said it was the egr. If the switch doesnt work than im gonna check the other vaccum lines.

kd3pc

you might check the TPS while you are in the area.

Chris_1

iTrader: (1)

Test the TPS before just randomly changing it would be a smarter approach.

Flashthompson

Already changed the TPS. Did that this morning. I did find a vaccum line that was unhooked from something that i have no clue what it is or does. Passenger side, behind the bumper and same height as the bumper. Small black box with 2 ***** on top. The vaccum line goes into a solenoid that goes with the EGR. On the other side it goes to the throttle body. Replaced those vac lines still nothing. Throttle still at ab 1000 when parked. And the truck still shudders when I give a little gas while driving.

raski

Probably something with the evap system. Look at the larger lines such as brake booster and pcv. Those will raise rpm/s more so than the small ones. An egr which is hanging slightly open will lean out mixture enough to raise rpms and cause stumble. On my f150 throttle body, the hardened steel throttle shaft wore grooves in the aluminum bore in the case causing the throttle not to close completely. I had a high idle which made the idle speed waver around. Also if someone "fooled" with the idle hard stop adjustment on the throttle body, it will hold the idle speed higher. When you cleaned the AIC, did you clean out the bore which it resides? Often a chunk of carbon forms there, causing the pintle on the AIC to hang up and has to be scrubbed out

Flashthompson

Well I have given up. I have checked and replaced the EGR, the sensor on top of the EGR, TPS, IAC, vac lines checked and cleaned the MAF sensor and the O2 sensor. Runs alot better, but still has a high idle but no codes. so mym last idea is a clogged fuel filter. Ill change it and if nothing then its goin in the shop.

Homewrecker302

my 95 sucked the throttle body gasket a year ago maybe check for that use a can of brake clean with the straw spraying around gasketed areas looking for leaks engine should bog if you find a vacuum leak

raski

I remember there was a TSB involving a revised T/B gasket.

(OP) usually a fuel filter will cause issues during peak engine demands such as hard accelleration. Sorry you changed all those parts w/o success. Your parts guy atleast made his boat payment. Keep us up to date.