Ok so quick update here - so I FINALLY found a can of the Seafoam and the problem COMPLETELY vanished - and has been vanished for 3-4 tank fulls of untreated gas.
So doe this basically tell us that it was simply clogged injectors the entire time?
Truck="missing"or"starving"engine of fuel during acceleration-EGRvalve or Injectors?
- Thread starter antman33
- Start date
Ok so quick update here - so I FINALLY found a can of the Seafoam and the problem COMPLETELY vanished - and has been vanished for 3-4 tank fulls of untreated gas.
So doe this basically tell us that it was simply clogged injectors the entire time?
Molson02536
New member
Most likely a clogged filter screen at the fuel sending unit. There is a screen at the pump and when it get's dirty and varnish forms from low fuel in the tank for a few days from oxidation fr om time to time will cause this.
Keep us posted and glad that you tried using Seafoam before you tore everything apart.
Ok, well sorry to be back on here bothering you all but it looks as though the exact issue is back again. Ugh, and this time I have tried 2 bottles of Sea Foam and an extra bottle of the "NAPA" brand equivalent ... all in separate full tanks of gas ... all to no avail.
The issue is exactly the same as before. Same symptoms to the letter. The truck misses or lags most when I am in the early stages of acceleration and generally happens much less if I give it more gas and accelerate faster.
The Sea Foam worked so well last time but this time, not at all.
Any ideas?
The issue is exactly the same as before. Same symptoms to the letter. The truck misses or lags most when I am in the early stages of acceleration and generally happens much less if I give it more gas and accelerate faster.
The Sea Foam worked so well last time but this time, not at all.
Any ideas?
bigmac
New member
Check fuel pressure regulator
Molson02536
New member
Go through your vacuum lines and recheck your fuel pressure regulator. From what you are describing to us. It sounds like your fuel pressure is low and or you have a knock sensor that is gone bad.
A knock sensor that has gone bad and is to sensitive will tune your timing back which will give you what your have indicated. A Tech 2 scanner will indicate if the sensor is bad and to sensitive as your engine is under load.
Good luck and keep us posted, but start with the simple. Recheck the vauum line and the fuel pressure regulator for leaks or to make sure it is regulating your fuel pressure.
Go through your vacuum lines and recheck your fuel pressure regulator. From what you are describing to us. It sounds like your fuel pressure is low and or you have a knock sensor that is gone bad.
A knock sensor that has gone bad and is to sensitive will tune your timing back which will give you what your have indicated. A Tech 2 scanner will indicate if the sensor is bad and to sensitive as your engine is under load.
Good luck and keep us posted, but start with the simple. Recheck the vauum line and the fuel pressure regulator for leaks or to make sure it is regulating your fuel pressure.
Ok, sorry for my dumb-ness but what/where exactly IS the "vacuum line" and "fuel pressure regulator". And while we are at it, where would the "knock sensor" located as well?
Also, any idea how I'd find a "Tech 2 Scanner"? Am I assuming correctly that this is something found only in a garage?
Molson02536
New member
Yes a Tech2 Scanner is at most garage and as mentioned, start with the fuel pump regulator and is along your fuel rail. I believe i posted it on a earlier post where the FPR (fuel pressure regulator) is.
The Tech2 Scanner can indicate if you have a knock sensor that is going bad, so start with the FPR first.
Good luck and keep us posted.
Newbee to the forum and saw this thread. I have been having the EXACT same problem with my 96 sonoma 2.2 man trans, 160xxx miles. Surges/hesitates/bucks, after shifting gears at 1/4 to half throttle, when I accelerate the problem seems to not be as noticible. This has been driving me crazy for about 3 months now. Replaced the TPS, plugs, wires, and both coils. I saw someone said to check out the FPR, so I did. No fuel came out so I followed the vacuume hose all the way back to the "ball" (vacuume resivor?) mounted to the hood and found the hose was brittle and cracked. I cut off the bad part but noticed there are other cracked spots along the hose.The truck seems a little better. Will be replacing all the vacuume hoses hopefully that does it, but probably won't as nothing is ever that easy for me. Will keep you guys posted.
Question, what is a normal idle rpm? Mine is at 1100-1200, after cutting off a part of the cracked hose it came down to about 1000.
Thanks for all the info and suggestions already, hopefully we can both solve these problems.
Question, what is a normal idle rpm? Mine is at 1100-1200, after cutting off a part of the cracked hose it came down to about 1000.
Thanks for all the info and suggestions already, hopefully we can both solve these problems.
First off newbee here and hello. Antman not trying to Jack your thread but I have to say I feel your pain. I am having the EXACT same issue with my sonoma, has been driving me crazy for about 3 months. 1996 2.2 man trans 160xxx miles. Surge/ hesitation/ buck after shifting gears when throttle is about 1/4 to half way, eccelerate and it seems to get better. Replaced TPS, plugs, wires, and both coils, also tried fuel injector cleaner. I saw a post saying to check the FPR, so I did. No fuel out of the vacuum hose but traced it back to the "ball" ( vacuum reservoir? ) mounted on the right side of the hood and found the hose brittle and cracked were it is connected. Cut off the bad part and reconnected but saw there are other parts of the hose that is cacked also. Truck felt a little better but there were still cracks in the hose. Going to replace all the vacuum hoses and hopefully that does it, but probably not as nothing ever is that easy for me. If that doesn't do it I will be removing and inspecting my EGR valve next. I work shift work and on nights now so first day off I will be replacing vacuum hoses and cleaning EGR. Will keep you posted.
Question, what is the normal idle rpm? Mine is at 1100-1200 rpms after cutting off Part of the bad hose it came down to about 1000 rpms. Could the symptoms that Antman and myself are seeing be a simple vacuum leak? Oh also I am not getting any codes or check engine light.
Thanks in advance...
Question, what is the normal idle rpm? Mine is at 1100-1200 rpms after cutting off Part of the bad hose it came down to about 1000 rpms. Could the symptoms that Antman and myself are seeing be a simple vacuum leak? Oh also I am not getting any codes or check engine light.
Thanks in advance...
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***update*** So I replaced the vacuum hose from the FPR to the "T" where it then connects to the vacuum reservoir attached to the hood. When i looked at it last night in the dark and I did not see there is another hose coming off the "T" and going down into the cab of the truck. That hose is brittle and shows some cracks also, but didn't get enough hose to replace that one too.
SO, the truck is running 100% better. overall I would say the problem is about 90% fixed, but i still have another hose I need to replace, and want to do the sea foam stuff as well.
Keeping my fingers crossed.
SO, the truck is running 100% better. overall I would say the problem is about 90% fixed, but i still have another hose I need to replace, and want to do the sea foam stuff as well.
Keeping my fingers crossed.
Ok so what you are saying is that I should check this specific hose under my hood and, if it shows any cracks or leaks, to simply replace the entire thing?
Yes I would start there atleast, replace any vacuum lines that are brittle or cracked. It definatly made an improvment for me but the problem is still there. Probably a combination of a few things. Going to remove and clean the EGR valve tomorrow.
*** Update *** So I removed the EGR valve and cleaned any carbon off that i could see. It was not that bad looking and Im not sure if it was actually stuck open. But that wasn't the problem because the truck is still having the same symptoms as before. So I drove the truck around trying to diagnose exactly when and how I feel the problem, and came to the conclusion that it seems like it only acts up at a certain throttle position. The first thing i replaced (2 months ago ) when trying to fix this issue was the TPS (throttle positioning sensor ) because the issue seemed to be at a certain throttle position. *** PROBLEM FIXED ***
Well to make a long story short the TPS that I got new turned out to be bad also, replaced it with another new one and I can not get the truck to duplicate any of the problems as before. So, don.t rule out something just because you already replaced it, could be faulty new in the box. OH and you can test your TPS with a multimeter, I just didn't have one.
Well to make a long story short the TPS that I got new turned out to be bad also, replaced it with another new one and I can not get the truck to duplicate any of the problems as before. So, don.t rule out something just because you already replaced it, could be faulty new in the box. OH and you can test your TPS with a multimeter, I just didn't have one.
Ok so where exactly is a TPS? I assume its under the hood, but where and are there any tricks to replacing it?
I believe I can get the part pretty easily from Napa, so It would simply be a matter of finding it, taking the old one out, and popping the new one in. Is it that simple?
Oh and what is a multimeter and where would I be able to get use of one?