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Username Post: 1990 Chevy Cheyenne 350 sluggish performance, code 42 and 44        (Topic#235154)
strictlygm 
Forum Newbie
Posts: 92

Age: 32
Loc: Wonder Lake, IL
Reg: 02-07-10
02-07-10 11:26 AM - Post#1858008    

First of all, I've got a 1990 Chevy Cheyenne C1500, 2WD, regular cab, long bed, THM400 trans, with a 350ci engine, basic work truck that my father had given me. I've had the truck since high school,{about 12 years} It's been a great truck so far and whenever something broke on it, I'de fix it myself. It originally had a 305ci engine in it, that I replaced with a 350ci crate engine {96 and later 350 crate with the vortech heads and roller cam/lifters} as far as I know I did everything correct when installing this new engine, I even got a new PROM chip installed in the ECM for the larger 350ci engine. I did this install when the truck had about 140,000 miles on it. The truck now has 214,000 miles on it and is starting to have problems with the engine performance. At first it started stalling whenever I made right hand turns, then it would just lack acceleration and felt like it was starving for fuel. I replaced the fuel injectors and rebuilt the TBI unit, changed the fuel filter,changed the fuel pump and fuel pump strainer, even put in a new fuel tank when changing the fuel pump{old tank was so rusty, you could punch a hole in it with your bare fist}, the stalling problem went away, but the engine still was strugling. Then one night I was driving home from school and the engine started running like crap and felt like it was going to quit,the service engine light came on, extracted code 42 and code 44, I've got the haynes manual and it states that code 42 is ignition control circuit[shorted circuit]and code 44 is lean exhaust. I went and checked all wiring under hood and found to be ok. Removed the ignition module from under distributor and had it tested at AutoZone, tested it 5 times and it passed. Changed the spark plugs,cap and rotor and wires, problem still there, checked the intake manifold for leaks with carb cleaner and found that the intake gaskets were leaking,{typical on the vortech head engines} so i did an intake job. After all that the problem was still there. the service engine light comes on and stays on until i put the trans in park or neutral, or turn the engine off and restart it, and it only comes on every now and then. I'm begining to think it has something to do with the knock sensor, or the ESC module located on the passenger side of the TBI unit. This problem does feel like an ignition timming problem, it feels like the ecm is retarding the timing, or not advancing it under load. Could it be that the knock sensor could be defective and not set its specific code? Or could the ESC module be defective? I'm not really familliar to this ESC system, all I know is that it has something to do with the timming on the engine. Any help or suggestions would be greatly appreciated.

 
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Chevytech 
Subject Matter Expert - Senior Member
Posts: 3068

Loc: Twin Cities, Minnesota, U...
Reg: 04-25-04
02-07-10 12:16 PM - Post#1858029    
    In response to strictlygm

A code 42 is set when the ECM loses communication with the distributor.

Code 42 can be set by a bad distributor module, a bad ECM or wiring problems between the ECM and distributor.

A code 42 will get set when the set timing connector is unplugged to set the timing. Make sure you clear the codes after setting the timing.

A bad distributor module is a common cause for this code.

  • Quote:
I'm begining to think it has something to do with the knock sensor, or the ESC module located on the passenger side of the TBI unit. This problem does feel like an ignition timming problem, it feels like the ecm is retarding the timing, or not advancing it under load. Could it be that the knock sensor could be defective and not set its specific code? Or could the ESC module be defective?

Knock sensor and Electronic spark control problems would set a code 43.

When the system detects a problem and sets a code 42, it runs in a backup mode where electronic spark timing control is not used, and the system runs with less timing advance. This may be what you are feeling.

If you clear the code 42, and it keeps returning and you find no wiring problems, check the condition of the connector terminals on the distributor module, and if they look good replace the distributor/ignition module.

I also suggest putting a fuel pressure gauge on it a testing the pressure with the engine running. These trucks have several problems that cause low fuel pressure including the fuel pressure regulator, fuel pump, fuel filter, and the hose that connects the fuel pump to the sending unit in the gas tank.

I realize you put in a new pump. Was it an aftermarket or an OEM pump?

I see it’s your first post. Welcome to the message board.

For those of you that are wondering why you are not getting replies to your thread:

Did you give the model, year, engine, fuel system type, and transmission information?

If the it has been altered from stock let us know about that too.


 
strictlygm 
Forum Newbie
Posts: 92

Age: 32
Loc: Wonder Lake, IL
Reg: 02-07-10
02-07-10 12:55 PM - Post#1858044    
    In response to Chevytech

Thank you for the welcoming and quick response. I'm wondering if the tan wire with black tracer that you unplug to set the base engine timming possibly has a bad connection, or like you suggested, a bad ignition module. I did remove this module and had it tested at AutoZone.(coincidentally there was another customer there with the same exact module, but out of a 4.3 astro van that had his tested and passed.) I had mine tested next and it passed, I had it go through the test 5 times and all 5 times it passed. Is this test really accurate? I know that alot of times this module will act up when it gets hot, but my problem is all the time. As for the fuel pump, I replaced it years ago when my rear main brake line ruptured, I removed the bed and fuel tank and ran all new fuel lines and brake lines in the rear.(alot easier to do with bed and tank removed)that was a good 10 years ago, and I replaced the fuel pump with an aftermarket pump only, from Autozone. Never had any problems with this pump. Just recently I replaced it again, but this time I went with a whole sending unit pump and all from Autozone, because the top part of the sending unit assembly was so rusty and didnt trust it to put back in,same with the tank. And hooking up a fuel pressure gauge is a little tricky on this TBI engine, as far as I know there is an inline shrader valve you can purchase to put inline with the fuel line, but not sure where to get it. The actual fuel pressure regulator located on top rear of the TBI was replaced, I replaced it when i rebuilt the TBI. I'm still thinking it has to be an electrical problem with the ignition control system, because of the code 42 and the sluggish performance as if the timing was off.

 
Chevytech 
Subject Matter Expert - Senior Member
Posts: 3068

Loc: Twin Cities, Minnesota, U...
Reg: 04-25-04
02-07-10 02:18 PM - Post#1858078    
    In response to strictlygm

  • strictlygm Said:
I did remove this module and had it tested at AutoZone.(coincidentally there was another customer there with the same exact module, but out of a 4.3 astro van that had his tested and passed.) I had mine tested next and it passed, I had it go through the test 5 times and all 5 times it passed. Is this test really accurate?........

No!
The test results from these store are not always accurate, and some times the will say the module is good when it is not, but for a free test that may find the problem it is worth a try.

  • strictlygm Said:
……..Never had any problems with this pump. Just recently I replaced it again, but this time I went with a whole sending unit pump and all from Autozone…..


I have seen so many pumps from other manufactures fail in the warranty period or just after the warranty is up that I suggest only using an OEM pump. This is another reason to test the fuel pressure if a new distributor module does not fix it.


  • strictlygm Said:
And hooking up a fuel pressure gauge is a little tricky on this TBI engine, as far as I know there is an inline shrader valve you can purchase to put inline with the fuel line, but not sure where to get it. The actual fuel pressure regulator located on top rear of the TBI was replaced, I replaced it when i rebuilt the TBI. I'm still thinking it has to be an electrical problem with the ignition control system, because of the code 42 and the sluggish performance as if the timing was off.

Yes, TBI trucks are not built with a fuel pressure test port. GM saved a few pennies per truck.

I agree that all the problems could be from a bad module.

Did you put heat sink compound/grease under the module when you installed it? Without it, the module will fail.


For those of you that are wondering why you are not getting replies to your thread:

Did you give the model, year, engine, fuel system type, and transmission information?

If the it has been altered from stock let us know about that too.


 
355Cheyenne 
Senior Member
Posts: 3765
355Cheyenne
Loc: Northern MN
Reg: 10-27-04
02-07-10 03:13 PM - Post#1858112    
    In response to Chevytech

I am with chevytech. Check fuel pressure, check wires comming off distributor.(maybe a rodent was hungry) and then replace module.
98 Silverado k1500 4x4 350


 
strictlygm 
Forum Newbie
Posts: 92

Age: 32
Loc: Wonder Lake, IL
Reg: 02-07-10
02-07-10 07:37 PM - Post#1858260    
    In response to 355Cheyenne

my dads got an old 89 Chevy G20 conversion van that he's going to get rid of. I'll take the module from that and try using it on my truck and see if there's any improvement. Money is kinda tight right now, and can't afford to buy new module, already spent alot of money on this truck. And yes there was the special grease underneath the module for the heat. Thank you for the suggestions, will keep the problem updated.

 
dabooge 
Forum Newbie
Posts: 6

Reg: 02-05-10
02-07-10 08:56 PM - Post#1858325    
    In response to strictlygm

If your getting code 44 I'm thinking you need to replace your oxygen sensor. Have you ever replaced it?

 
strictlygm 
Forum Newbie
Posts: 92

Age: 32
Loc: Wonder Lake, IL
Reg: 02-07-10
02-08-10 05:51 PM - Post#1858863    
    In response to dabooge

yeah, I replaced the oxygen sensor, and have not seen code 44 since.

 
vtx_copper 
Forum Newbie
Posts: 1

Reg: 07-30-10
07-31-10 07:22 AM - Post#1953392    
    In response to strictlygm

Did u ever fix your problem I have the same problem with my truck?

 
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