code question for 1990 F150 5.0L

Reply Subscribe

Thread Tools

Search this Thread

May 22, 2005 | 12:04 PM

moebdick

Thread Starter

Elder User

Joined: Sep 2004

Posts: 821

Likes: 1

From: Nashville

code question for 1990 F150 5.0L

I have a 1990 F150 5.0L that has an idle problem. Truck would start up fine and run normal for a few minutes, but then the idle speed would abruptly jump to >2000 rpm.

I ran a KOEO and got codes 23 and 53. Ran KOER and got 98 and 53. Since codes 23 and 53 are throttle position sensor codes, I checked the sensor as recommended by Haynes using volt/ohm meter and found it was out of range, so I'm replacing it.

Code 98 in KOER is "Hard fault present". What does this mean?

Also, I took the throttle body off to get at the TP sensor and found the intake manifold throat all gunked up with carbon in the area by the [expletive] EGR valve intake port. The stuff is caked on and kind of hard, but I can break it loose with my fingers if I pick at it. Seems like this junk would be bad news for the engine if bits of it broke loose? Should I clean this stuff out, and if so, is it necessary to remove intake manifold to clean, or can I clean it on and just vacuum it out with a shop vac afterward?

Any other issues I should be aware of on this fix?

Thanks for any advice/help.

May 23, 2005 | 07:54 AM

moebdick

Thread Starter

Elder User

Joined: Sep 2004

Posts: 821

Likes: 1

From: Nashville

bump ... Nobody knows what code 98 means?

May 23, 2005 | 09:22 AM

Putt

Posting Guru

Joined: Jul 2003

Posts: 2,232

Likes: 1

From: Colville, Washington

I think the 98 means there is a constant failure in a sensor, in this case the TPS was out of range. I am not however an expert on the codes, so take that for what it is worth.