12 replies to this topic

[Zx12richard]

Tried the vacuum leak thing 3 times used can of starting fluid each time around intake. Tried three different used mass air units.


Put it in shop they said fuel pressure at idle good but showing 25%lean,they found no vacuum leaks. Changed fuel filter. They were 95% sure it was mass air unit. I bought a new gm mass air for 300 bucks. They was wrong.

I read some about map sensors, so I reset codes unplugged map sensor. Truck physically ran better than it had in a long time. I run 180 miles and check three times. Only code came up was map sensor cause it was unplugged. No 171 or 174. So i thought hey thats it. I got a really clean map sensor from a salvage yard dont wanna spend 65 bucks and be wrong. Cleaned it with carb cleaner then installed truck coded withint 20 miles.

171 and 174 back. Filters a k&n and clean.

Other misc codes it originally had was random misfire po300 po102 maf.

Thanks for any help or thoughts in advance.

[Zx12richard]

Forgot to mention. I do have a problem in the heating unit that could be a vacuum leak. Could something in the hvac trigger the 171 174 codes. Could I plug the main hvac line and see if it recodes?

[jackn7]

Forgot to mention. I do have a problem in the heating unit that could be a vacuum leak. Could something in the hvac trigger the 171 174 codes. Could I plug the main hvac line and see if it recodes?

I had the same codes showing replaced the maf sensor and still showed ses code (171 and 174) finally figured out it was the rubber elbow directly behind the air intake above the throttle body. It looked ok but was just loose enough to let air in. Did a quiclie repair job with a couple of hose clamps and haven't had a problem since.

[Zx12richard]

Thanks trying it. Can't hurt.

[Zx12richard]

Unplug map sensor lean conditions disappear. Tried a used map sensor and lean came back.

[rustyg]

Wiring is F-ed

[Zx12richard]

Well my lean codes turned out to be fuel pump.Some of my random misfire was wires. Hoping new ac delco iridium plugs will make the rest to away. Looked like fouth of July under hood the other night when looking for misfires.

[Bobbing]

Well my lean codes turned out to be fuel pump.Some of my random misfire was wires. Hoping new ac delco iridium plugs will make the rest to away. Looked like fouth of July under hood the other night when looking for misfires.

Fuel pressure was lower than 50psi?

[Zx12richard]

I didn't personally check it. Shop said it was right at lower limit. But fuel pump did fix it. Filter was extremely dirty.

[Slick1]

I had the same codes showing replaced the maf sensor and still showed ses code (171 and 174) finally figured out it was the rubber elbow directly behind the air intake above the throttle body. It looked ok but was just loose enough to let air in. Did a quiclie repair job with a couple of hose clamps and haven't had a problem since.

Well my lean codes turned out to be fuel pump.Some of my random misfire was wires. Hoping new ac delco iridium plugs will make the rest to away. Looked like fouth of July under hood the other night when looking for misfires.

I was having the same problems with it running lean and bucking on me a driving like total ass. After replacing the fuel filter and pump it still did it and it turned out it was a tear in the bonnet (top part of the intake that clamps to the throttle body).

Tiny cause, HUGE problems.

[QuickSilverAWD]

That's why you should upgrade to an AEM Bruteforce style intake like the one I have for sale. No worries about crummy factory restrictions and get better gas mileage.

[Slick1]

That's why you should upgrade to an AEM Bruteforce style intake like the one I have for sale. No worries about crummy factory restrictions and get better gas mileage.

Talk about a sales plug

Edited by Slick1, 25 May 2011 - 10:21 PM.

[QuickSilverAWD]