Engine Problems

[MrQ]

My engine seems to have a real issue after me driving it for a few minutes. It loses all power, the RPMs dip to 500 and below, and the whole truck starts to shake. I have replaced the computer, checked the wires, and checked the codes. The only codes I can pull are 5 flashes for the instant memory. Which as far as I know, means absolutely nothing.

 

[rhauf]

maybe try another code scanner?

i'd also suggest (as strange as it sounds) unplugging sensors (such as TPS and MAF, maybe o2 etc)and seeing if things change. you can do it while it's running. i've had sensors go bad before and cause crazy issues such as that, without throwing a code. (for me it was the MAF, there was a fiber from the air cleaner stuck in it)

when you unplug a sensor, the system will go into the error mode, and guess on the reading for that sensor (using a map or something) anyway it just sorta seems to work for troubleshooting sometimes.

it's not overheating, is it?

 

[beyerodeath]

was having pretty much the same problem, it would do the same thing but eventually it acted like the torque convertor was locked up. ran the scanner on it and no codes. turns out it was a vaccum problem from the cruise control. check your lines. wish i would have before i replaced the t/c.

 

[Willard]

Vacuum is possible, I would also test the resistance of the coil pack. I have gone through two, and generally the warmer the motor got the worse the coil pack got.

 

[MrShorty]

In addition to the above, I'd put a fuel pressure gauge on it and see if the fuel system is operating properly.

 

[MrQ]

Actually it was the FP relay. It was pretty toasted. Put the new one in and drove it around it on the highway, no problems.

 

[MrShorty]

Since diagnosis is so much of the battle, would you elaborate on how you determined the relay was bad?

 

[Hitchhikingmike]

Glad you found the problem. Please elaborate on how you determined it was the relay. Relays really don't stop working intermediately, it usually either works, or it doesn't.

 

[MrQ]

Turns out the relay was only part of the problem. Now I start to get a clank when I have the A/C on the engine still runs real rough and it can't seem to find the sweet spot to idle at.

Codes pulled:

KOEO
539

CM
58
72

KOER
116

 

[Iron Weasel]

KOEO 539 - A/C or defrost "ON" during Self-Test.

KOER 116 - Engine coolant temperature higher or lower than expected.

Can't find anything in Alldata for the continuous monitor codes 58 & 72.

 

[Hitchhikingmike]

The only mechanical parts capable of making clanking noises in the A/C system is the compressor... sounds like it may be tearing itself apart.

 

[MrQ]

I'd rather have that than the engine making that noise...

 

[MrShorty]

The CM codes should be three digit codes, just like the KOER and KOEO codes. Any chance those are 158 and 172 codes??

KOER 116 is usually a result of the engine not being warm enough before initiating the test. Make sure the engine is fully warmed up before performing the test. If the engine is unable to warm up, make sure the thermostat is closing when it should.

KOEO 539 indicates that the AC switch on the dash is turned on. Turning it off should clear this code.

 

[MrQ]

THANKS SHORTY!!

That was the answer I was looking for. I think I was tired when I read those codes. I was leaning toward the O2 sensor originally, but the codes I (incorrectly) read didn't confirm. Pays to have people double check your work, I guess.

 

[nascar_intimid]

yeah......

Shorty is worth his weight in gold!!!! helped me many times in the past..... years ago!!!!