Weird drivability issue

[25Horseplay]

The car is My 89 L 4 speed. (carb) It runs and idles really good, but when you go to take off it bogs down. It will stall if you don't feather the gas to get going. After you are moving along it is OK. It seems like it pops through the carb when it does this. I also noticed it was high on the NOX for it emissions test. I am not sure it is carb related or not, any thoughts?

[smokin fastiva]

nox is nitrides of oxygen. im a diesel mechanic and i know that in a diesel engine high levels of nox is caused by high exhaust gas temperature. it could be the same in a gas engine but im not sure.

[b3 madness]

I would guess that your carb's accelerator pump may not be functioning properly. It may be time for a rebuild of the carb.

[Pu241]

nox is nitrides of oxygen.

NOx are nitrogen oxides specifically NO(Nitrogen oxide) and NO2(Nitrogen Dioxide), also known as Mono - Nitrogen Oxides.
There are no nitrides of oxygen.
I know a little about chemistry

im a diesel mechanic and i know that in a diesel engine high levels of nox is caused by high exhaust gas temperature. it could be the same in a gas engine but im not sure.

It is the same in a spark ignition engine. except that in gas fired auto engine we have a EGR valve (Exhaust Gas Recirculation) which introduces, of all things, exhaust gas back into the cylinder to reduce peak temperatures and shift the equilibrium of the combustion products of gasoline in air (78% Nitrogen) under pressure to a point of less NOx production. If this valve fails then peak temps are increased and no shift in the NOx production occurs and NOx reading are high. May also hear pinging as those peak temps may leave the cylinder and any carbon residue hot enough to induce pre-ignition or knocking.

im a diesel mechanic

Great I have question you might be able to answer concerning IP's.
Mind if I PM you?

[smokin fastiva]

yeah theyre using EGR on diesel engines now also to cool EGT's. im still in college for diesel right now. i graduate in january of 08 but i have already completed my basic and advanced fuel classes so i may be able to answer your question.

[Pu241]

Re: Weird drivability issue

I also noticed it was high on the NOX for it emissions test. I am not sure it is carb related or not, any thoughts?

I'm not sure when the the EGR does it stuff, but I do know that emissions are greatest under acceleration, so makes sense that it would be running then.
But I thought EGR was engaged at anything above idle. And emissions testing is done at some rpm above idle so that makes sense too.

I vote for the EGR valve!

[25Horseplay]

Those are the things I was thinkng it might be just wanted to see what others thought. I will start by checking the EGR and maybe rebuild the carb.

[TominMO]

Wouldn't hurt to check the PCV valve; make sure the ball rattles. But accelerator pump is also a good candidate.

Can these carbs be adjusted for idle mixture or is that screw behind a little cover? If so, you can drill out the cover and fiddle with the idle mixture adjustment. I only mention this because on Weber carbs you can adjust idle mixture. Incorrect mixture causes stumbling off idle.

[25Horseplay]

The PCV is OK, I checked that out. It idles great! The only problem is a stumble/bog when taking off in first gear, as soon as its going it is OK.

[worfdog]

pull the air cleaner off, with engine off ,work the throttle and look inside the carb.if you do not see gas squirting inside, the acclerator pump is not working.it can be replaced without removing the carb.a bad acel. pump will cause your kind of problem.

[Pgh5spd]

Fuel filter could be partly clogged too

[WmWatt]

I suspect high NOx and low power are separate issues. I had high NOx with normal power. Heres' a description of testing and cleaning the EGR valve on my carb'd '89 www.ncf.ca/~ag384/EGRvalve.txt

[25Horseplay]

Last night I ordered a carb rebuild kit and a EGR gasket. I will work on it Sunday.