Need help on 06' GM hummer H3 3.5liter DTC

[Sffred]

Hello,

 

My mother has a GM Hummer H3 (2006, 3.5l) and has a few codes

1.Manifold absolute pressure sensor

2.Coolant temperature sensor

3.Cylinder misfire #2

 

So I replaced the MAP sensor (OEM), Coolant temp sensor (AC Delco with 15mm crowfoot), and all 5 coil packs and all 5 sparkplugs too (NGK plugs)

 

And the misfire went away, but the MAP and the CTS code came back? (I know the sensors is good I replaced them with brand new?)

 

What I did notice is that the temp gauge only reads 1/4 of normal, and the fans turns on too early (not even getting near half way mark on the temp gauge).

 

And I just checked the resevoir and its low on coolant? What could it be?

Unfortunately my mother is going thru remission (unemployed because of her cancer) and cannot afford a shop, so she asked me to help.

 

Any help is greatly appreciated, and thank you in advance from me,

Fred

[Sffred]

Okay, checked the OBD2 with my scanner and only (2) codes showed up

P0128

P0128 pending

 

Went to autozone and grabbed a Tstat and Tstat housing for $49.99 and couple gallons of coolant, and swapped out the part. Done.

 

Erased the CEL and bled' the coolant using a gravity funnel, and pinched the reservoir tube. Ran the car for about 10 min, and then another 5min with the heater full hot on low power (to cycle coolant in the heater core). And now the temp level is in the middle.

 

Going to go run errands with moms so we can add some mileage and I'm hoping (fingers crossed) that the CEL will go away.

 

I did notice that the original thermostat was missing the bar in hole. And the aftermarket one had it still in tact.

 

Thanks (I'll keep y'all posted)

Fred

[Chris]

Possibly a thermostat and as for the MAP sensor, look for a vacuum leak or swap the sensor you got out under warranty

[Sffred]

Ok I'll buy a thermostat and housing. Hopefully it will help thanks. As for the MAP sensor, I already replaced it with new? I'm fearing of replacing the intake manifold. iirc I've heard the plastic intake manifold were known to crack. FML

[Sffred]

Did a couple errands and CEL is on again! FML ,went back to moms house scanned it and now it says P0302 cylinder 2 misfire? I don't know what to do now?

[Colossus]

Gah. The 3.5L is such a POS. My brother and his wife have an 07 Hummer with that crappy way underpowered engine and all kinds of problems. Good luck on yours.

[Colossus]

Ok thanks. Go ahead and do what Fred suggested and report back. Also re-check the gap on the plugs. Just because they say they come pre-gapped doesn't mean you should believe it.

[Sffred]

125k

[Colossus]

Should have used AD/Delco plugs, the same type that came in the vehicle from the factory. You might have gotten a bad coil even though it is new. Pull the plugs and wires and have a looksie.

[Jsdirt]

Time to play swaparoo with the coils - if the problem follows that particular coil, you've found the problem. If not, you'll need to see if the signal to fire is reaching that coil.

 

If that all checks out, time for compression & leak down tests, starting with that cylinder.

[Colossus]

Good tip, JS. Fred- how many miles?

[Jsdirt]

Just because parts are new doesn't mean they are good and functional. Welcome to the 21st century - unfortunately this is the new normal ...

 

Glad your mom is in remission. F**k cancer.

[Sffred]

125k

[Colossus]

You can F*** cancer all you want, but it doesn't care.