Sonoma v6 accelerates like crap sometimes

[Brandon87]

some days the hesitation is worse than other days. My truck decides when it wants to accelerate like crap. The only way I can describe it is that its like a stuttering shuttering jerky hesitation and it only happens around 5 or 10 mph. I do not get any check engine lights. So far I have replaced the fuel injectors, Fuel pressure regulator, Throttle position sensor, Rotor cap, spark plugs, fuel filter. What do you think it could be? ignition coil? IAC? the distributor rotor? EGR valve? Sometimes it has a very hard time starting and the only way it will fire up is if I turn the ignition on and off 3 or 5 times... I need some opinions please because this is driving me crazy.

[oldscsc]

Ignition cycling getting the pickup running indicates fuel pressure is bleeding off or insufficient.

 

Do a fuel pressure test to see what kind of pressure you're getting at the rail.

[Brandon87]

Ignition cycling getting the pickup running indicates fuel pressure is bleeding off or insufficient.

 

Do a fuel pressure test to see what kind of pressure you're getting at the rail.

I am going to try and get a hold of a fuel pressure gauge tomorrow. I will post results of I get a gauge.

[Brandon87]

I couldn't find a fuel pressure gauge today so I will try to find one tomorrow sometime. I took the EGR valve out today to clean it and come to find out its not an EGR valve its actually a Delphi 1997277 vapor canister purge valve. So this leads me to believe I have an old engine in my 2002 sonoma. I also took the IAC (idle air control valve) off and cleaned it up good, it had a fair amount of carbon build up. I did all of this and it didn't fix a thing but I am glad to get it done anyway. I will update as soon as I find a fuel pressure gauge.

[oldscsc]

Your pickup has EGR. You may be looking at the wrong component. I don't see why you'd have an older engine installed; a quick Google search shows that part was installed on the S10 family of trucks in your body style.

 

Cleaning that EGR valve and its passages is a good idea as they tend to get carboned up; however, I'm still betting on insufficient fuel pressure being the the culprit.

[Brandon87]

Your pickup has EGR. You may be looking at the wrong component. I don't see why you'd have an older engine installed; a quick Google search shows that part was installed on the S10 family of trucks in your body style.

 

Cleaning that EGR valve and its passages is a good idea as they tend to get carboned up; however, I'm still betting on insufficient fuel pressure being the the culprit.

Maybe I did over look the EGR.. The only thing that even looks like an EGR is that vapor canister.. Tomorrow is a new day so I will check it out and look harder for the EGR valve.. I will update tomorrow.. is it possible that maybe my 6 vortec dont have EGR?

[Brandon87]

I took another look this morning and I dont see any EGR, I read somewhere that 2002 models with the v6 vortec dont have an EGR..

[bjd2014lt]

My stepdads gmc jimmy did this also and it was the spider injection in the intake bout a 250 fix but ran geeat afterwards... always had a hard time starting and missing and jerking when taking off. Smooth now

[NoProblem]

My 2000 S-10 4.3 did the same thing - replacing the distributor fixed it.

[Brandon87]

My stepdads gmc jimmy did this also and it was the spider injection in the intake bout a 250 fix but ran geeat afterwards... always had a hard time starting and missing and jerking when taking off. Smooth now

 

I replaced the spider injection to a newer Multi port fuel injection spider just back in december

[Brandon87]

My 2000 S-10 4.3 did the same thing - replacing the distributor fixed it.

I replaced the cap but not the whole distributor, I have thoght about and likely will do it once i rule some other things out

[Jerry28]

I had similar problems before, both the hesitation, shaking, and hard starting. I too started with with fuel system, but always had good pressure. After finding the info on several other forums, I decided to replace the coolant temp sensor. This was on a 4.3 vortec, around a 2000 model. It had two separate coolant temp sensors, one for the gauge and one for the computer. The one for the computer was bad. It makes sense because the computer uses, among other things, that sensor to determine air/fuel ratio. Sometimes they will throw a code, but it did not in my case. Its like an 8 dollar part, so worth a shot if you still haven't figured it out!

[oldscsc]

Don't throw a coolant temp sensor at the truck without testing your current sensor.

 

Let the truck sit overnight, then hook up a scantool. Turn the key to the "run" position. Look for the coolant temperature PID.

 

Any basic scanner will be able to display this info. The coolant temp displayed on the scantool should be within a couple degrees of the ambient temperature.

[Brandon87]

Don't throw a coolant temp sensor at the truck without testing your current sensor.

 

Let the truck sit overnight, then hook up a scantool. Turn the key to the "run" position. Look for the coolant temperature PID.

 

Any basic scanner will be able to display this info. The coolant temp displayed on the scantool should be within a couple degrees of the ambient temperature.

 

Where is this temp sensor located?

[Brandon87]

I had similar problems before, both the hesitation, shaking, and hard starting. I too started with with fuel system, but always had good pressure. After finding the info on several other forums, I decided to replace the coolant temp sensor. This was on a 4.3 vortec, around a 2000 model. It had two separate coolant temp sensors, one for the gauge and one for the computer. The one for the computer was bad. It makes sense because the computer uses, among other things, that sensor to determine air/fuel ratio. Sometimes they will throw a code, but it did not in my case. Its like an 8 dollar part, so worth a shot if you still haven't figured it out!

 

I'm going to check in to this, Wouldn't a bad temp sensor set the check engine light off?