Engine no acceleration

[Uncleenvoy]

@Mooseman. @MRRSM @gmcman @NJTB @xavierny25 @JayArr
Drove this thing all week..put about 150 miles one her and all good other than the abs stuff. Did all the final checks and cleaning..the buyer came to take it for a drive and after 10 minutes..no acceleration from dead stop..no check engine lights.no pending.i dont even know what or where to look..only thing i can see is the evap monitor is still incomplete..and ive driven, idled ,let it cool down, and brought it back up to temp but still incomplete..no sputtering it just revs and wont go

Any suggestions

Gonna check fluid levels now..i saw no drips from underneath

This all happened late last night..im driving it for the first time since then right now and everything is good..slight gas smell though

It just started happening again after about 15 mins driving..im thinking its a fuel issue now that im alone and have time to think..im flooring the pedal and barley any acceleration but rpms dont go past 2100 2300..my biggest concern was that something was wrong with the transmission..but with no rpm movement at wide open throttle i think i can rule that out..anyone concur

 

[JayArr]

I would think that if the transmission was the problem you could still red line the engine. Is there any difference in max RPM in Neutral or Park?

Could be a vacuum leak, do you have an old school vac gauge?

I used to get a slight gas smell when my cat was clogged, haven't noticed it since I put a new one in. If you tap the cat GENTLY with a hammer does anything improve? How are your O2 sensor readings? A clogged cat restricts the engine.

 

[Mooseman]

To see if it's a clogged cat, remove the upstream O2 sensor and drive it. If it improves, it's the cat.

 

[Uncleenvoy]

Wouldnt i get a p0420 with a messed up cat

 

[Uncleenvoy]

Havent gotten a chance to do anything yet..but looked up cat prices...surprisingly lower cost than i expected..i thought they would start somewhere in the 300 range

 

[Uncleenvoy]

I was gonna check the fuel pressure first but the kit i bought doesnt fit..anybody know what adapter is needed for the test port to attach to my gauge. is that a schrader valve or some gm specific thing?and what is the proper operating psi..

 

[Uncleenvoy]

Will this work? its harbor freight part #62623
It says it doesnt fit gm throttle body sytems in the description..is that different from the inline test port?

 

[Mooseman]

Wouldnt i get a p0420 with a messed up cat

No necessarily. What little is still flowing could be cleaning the exhaust and not tripping the O2 sensor. It doesn't check for flow.

anybody know what adapter is needed for the test port to attach to my gauge.

AFAIK, it's the usual GM test port, whether at the filter (02-04) or on the fuel rail (05+).

 

[gmcman]

Put the trans in Park, step on the gas, does it rev to 3500-4000?

Put the trans in Drive, step on the brake and then apply the gas, does it rev to about 2200? The stall speed on these torque converters is about 2200 RPM.


Place the trans in 2nd from a standstill, does it drive away?
Need more clarification to determine what the issue might be.

 

[gmcman]

Any updates @Uncleenvoy ?

 

[Uncleenvoy]

Crazy busy last 2 days..couldnt get to do anything..im literraly sitting at my window waiting for the sun to come up..sunrise supposed to be 6:38..actually im gonna grab some breakfast at mcdonalds and by the time im done eating i can get started

 

[Uncleenvoy]

Banged on the cat as per @JayArr no change..gonna remove 02 sensor now..probably should change this air filter huh?forgot to check 02 sensor readings ..gonna put it back together and do that first

 

[Uncleenvoy]

Sensor one seems good... .05 to.86 back and forth..but sensor 2 us jumping stays at .72 range for a while then drops to .05 .065 and comes back up..probably the clogged cat then? Should i even bother taking out the upstream sensor?

 

[gmcman]

Did you see my post from Monday?

 

[Uncleenvoy]

Maybe banging on the cat worked..shes running fine now..02 sensor 2 has been holding steady in the .740 to .755 range fir about 10 minutes now..and i jyst drive it up and down a few blocks no problem..40 minutes ago it only took 1 minute and a half mile to start failing

 

[Mooseman]

I think it's still a good idea to pull the upstream sensor. Just because the downstream sensor is steady indicating a working cat, it doesn't mean it's not plugged. That and fuel pressure check.

Edit: Looks like we cross posted. So the cat may be at fault.

 

[Uncleenvoy]

@gmcman yea..i just did what u said and thats how i came to realize that its working fine now..like i said i started it up fom a cold start @ 7:22 am and by 7:25 and 2 blocks driving it started failing..barely enough power to get it back in the driveway..while monitoring the 02 sensors i saw your post and the rpms were back up and its driving fine now

 

[Uncleenvoy]

Im gonna go ahead and change the cat..ive got new bolts on the exhaust manifold end so they should come out easy..i hope the other end isnt rusted too bad so i dont have to take the entire exhaust out

 

[Uncleenvoy]

Now its doing it again.. @gmcman it revs to 4500 in park..max 2195 in drive with foot on brake and yes it drives fine in 2nd from standstill
And 02 sensor #2 is steady. .95 to.96

 

[Uncleenvoy]

Maybe too much trans fluid? Should i take a quart out?

 

[Uncleenvoy]

And now my fuel trims are way up and 02 sensor #1 isnt fluctuating..steady .045 to .05 at idle

 

[Uncleenvoy]

Dammit...a P0756 just popped up

 

[Mooseman]

I've had slightly overfilled trannys like that and never had anything like that happen. However that code could explain things if it's stuck in between shifts or something. And you say it's fine starting from 2nd gear.

You're likely to get a lean code with those trims unless the sensor itself is defective.

 

[TJBaker57]

Solenoid B stuck....

 

[Uncleenvoy]

But is P0756 the cause if the problem or the symptom..because with the slow acceleration im experiencing once it gets up to speed and goes into second then it performs normal..and yes it drives fine in 2nd then i put it back to D when 2nd is revving too high and all is well

 

[Uncleenvoy]

I got the lean code last week but that was when i forgot to reconnect the pcv and brake boost hoses

 

[Uncleenvoy]

Which one is solenoid B when i take off the pan?drivers or passenger side?

 

[TJBaker57]

But is P0756 the cause if the problem or the symptom..because with the slow acceleration im experiencing once it gets up to speed and goes into second then it performs normal..and yes it drives fine in 2nd then i put it back to D when 2nd is revving too high and all is well

The code P0756 sets when the PCM sees conditions that don't match what should be happening if the solenoids were where they were commanded to be.

Like the PCM commands the solenoids to be where they should be for 1st gear but the gear ratio the PCM sees isn't right for 1st gear. Does that make sense to you?

 

[Uncleenvoy]

Yes makes sense..wondering if i caused that code when i switched it from 2nd to D while driving just now

 

[TJBaker57]

Which one is solenoid B when i take off the pan?drivers or passenger side?

As I understand it the solenoids used to be called A and B. Then they changed the names to 1-2 and 2-3

 

[Uncleenvoy]

And solenoid B is for the 2-3 shift

 

[TJBaker57]

Yes makes sense..wondering if i caused that code when i switched it from 2nd to D while driving just now

In the picture I posted you can see a "fail case 1" and a "fail case 2". I think this code sets for either on or the other of these 2 fail cases.

I have no actual experience working on automatic transmissions so I can only say what I'm reading here.

 

[Uncleenvoy]

Yea..just need to know which one it is physically when im under there so i change the right one..or should i just change them both .i think i saw them for about 10bux each

 

[Uncleenvoy]

@TJBaker57 understood brother all help/suggestions are welcome something u say or post might trigger a solution with me or any of the other members

 

[TJBaker57]

And solenoid B is for the 2-3 shift

I think you have a book with something like this that tells when each solenoid is on or off??

 

[Uncleenvoy]

Yeah cant find my book

 

[TJBaker57]

Yea..just need to know which one it is physically when im under there so i change the right one..or should i just change them both .i think i saw them for about 10bux each

So remember... This code does not mean the electrical part is definitely bad. Some part could be just "stuck". The solenoid could be doing everything right electrcially but the mechanical business could be stuck.

 

[Uncleenvoy]

Ill try and move the valve with a screwdriver to see if it moves freely and spring back if that one has a spring in it..hopefully i can do that without having to take the valve body out

 

[Uncleenvoy]

I tested them like that b4 i reinstalled but hey u never know

 

[Uncleenvoy]

The p0171 too lean code just popped up..and 02 sensor #2 is all iver the place again