Idle and Lean issue

[Sy#1991]

Got the truck up and running with datamaster after doing new ngk plugs, taylor wires, cap, rotor ,coil, silicone vac hoses, johnson ic pump, rubber ic hoses, new t-stat and set base timing with wire unplugged. Before i did all the upgrades I had a rough idle (not misfire) but would idle surge a little, since the upgrades its still there but not as bad. If you blip the throttle a couple times it wants to stall out. On DM everything looks good except the S-term values are in the 140-148 range, which would be lean if I am correct. I sparyed down the entire engine looking for a vacuum leak and did not come up with anything. So I put on a fuel psi gauge to check fuel and at prime I have 42psi and 35 psi running (seems kind of low to me but have not checked spec. yet) Any help would be greatly appreciated. Sorry for the long post but wanted to give background info on it. Thanks

 

[syclone rider]

Re: Idle and Lean issue

Man I'm having the same issue with mine to the T I hope somebody can me and you both. Mine idles pretty good until it gets warm then does the same things your saying. Also my wideband gauge reads lean when it starts doing it. It will go lean then to perfect I don't understand it.

 

[nonova0074]

Re: Idle and Lean issue

I had the same problem then, I put in a turbo tweak chip and problems solved. Really its like I have a whole new truck, first it was a dog and my gn would rip it a part now its up to par. Thanks Eric!

 

[Don W.]

Re: Idle and Lean issue

I had the same problem then, I put in a turbo tweak chip and problems solved. Really its like I have a whole new truck, first it was a dog and my gn would rip it a part now its up to par. Thanks Eric!

So Turbo Tweak chips are in production?

To answer the question I dealt with this issue for a couple of years before pulling the lower intake and finding the gasket blown on the valley side. Using the bicycle tube trick to pressurize the intake I could hear the leak but could never find it. Well no wonder, the leak was on the valley side.

Just what you need to do, I know. Pull the lower intake. :-( But it's the only 100% sure way to know you don't have a bad intake gasket.

 

[Sy#1991]

Re: Idle and Lean issue

I dont want to have the chip tuned, I know something is not right. It should run better cause it low mileage and its pretty much factory, only has reliable upgrades. I just need it to run like factory again before I really start beefing it up.

 

[Sy#1991]

Re: Idle and Lean issue

:

So Turbo Tweak chips are in production?

To answer the question I dealt with this issue for a couple of years before pulling the lower intake and finding the gasket blown on the valley side. Using the bicycle tube trick to pressurize the intake I could hear the leak but could never find it. Well no wonder, the leak was on the valley side.

Just what you need to do, I know. Pull the lower intake. :-( But it's the only 100% sure way to know you don't have a bad intake gasket.

I know the intake gasket was done before I bought it, it was done at a GM dealer. Not saying that the tech didnt mess anything up, I work in the trade and have seen what techs have put together before

 

[nonova0074]

Re: Idle and Lean issue

So Turbo Tweak chips are in production?

To answer the question I dealt with this issue for a couple of years before pulling the lower intake and finding the gasket blown on the valley side. Using the bicycle tube trick to pressurize the intake I could hear the leak but could never find it. Well no wonder, the leak was on the valley side.

Just what you need to do, I know. Pull the lower intake. :-( But it's the only 100% sure way to know you don't have a bad intake gasket.

Pre-production, also what kind of NGK plugs are you using?

 

[Don W.]

Re: Idle and Lean issue

Pre-production, also what kind of NGK plugs are you using?

NGK UR6IX gaped, I think, to .028. They've been in there a year so I suppose I should look at them. :rotf: Wires are 3-4 years old and cap and rotor are at least a year. Not bragging just that the truck is running so good I hate to fool with it right now. :roll:

 

[nonova0074]

Re: Idle and Lean issue

NGK UR6IX gaped, I think, to .028. They've been in there a year so I suppose I should look at them. :rotf: Wires are 3-4 years old and cap and rotor are at least a year. Not bragging just that the truck is running so good I hate to fool with it right now. :roll:

HAHA I f'ed up my quote , thats great your truck is running awesome Don:tup:, but s-clone what plugs?

 

[Don W.]

Re: Idle and Lean issue

:


I know the intake gasket was done before I bought it, it was done at a GM dealer. Not saying that the tech didnt mess anything up, I work in the trade and have seen what techs have put together before

Cool. Some other things come to mind. It's my understanding that these motors don't idle real smooth anyway. Remove throttle body and IAC, check and clean. Run some real good inj cleaner through the system. If anyone has broken the seal on the throttle stop (AKA idle adjustment screw.) reset that so IAC has full control. Worn shaft/bearings on TB allowing a leak and/or a different idle every time you let up on it. Leaky EGR. A misstep on the silicone hose install. Leaky FPR. Check that ALL manifold (upper and lower) bolts are tight. I have Taylor wires. it can be an issue knowing that they are fully seated on the plugs.

Best I can do for now.

 

[Sy#1991]

Re: Idle and Lean issue

HAHA I f'ed up my quote , thats great your truck is running awesome Don:tup:, but s-clone what plugs?

I have the NGK UR5 gapped at .028

 

[Sy#1991]

Re: Idle and Lean issue

Cool. Some other things come to mind. It's my understanding that these motors don't idle real smooth anyway. Remove throttle body and IAC, check and clean. Run some real good inj cleaner through the system. If anyone has broken the seal on the throttle stop (AKA idle adjustment screw.) reset that so IAC has full control. Worn shaft/bearings on TB allowing a leak and/or a different idle every time you let up on it. Leaky EGR. A misstep on the silicone hose install. Leaky FPR. Check that ALL manifold (upper and lower) bolts are tight. I have Taylor wires. it can be an issue knowing that they are fully seated on the plugs.

Best I can do for now.

The TB is clean because checked that when I had the upper ic off to do the work. I know the vac lines are on correct because I double and triple checked them. I will try to get a DM file posted as soon as I figure out how to post it.

 

[Don W.]

Re: Idle and Lean issue

The TB is clean because checked that when I had the upper ic off to do the work. I know the vac lines are on correct because I double and triple checked them. I will try to get a DM file posted as soon as I figure out how to post it.

No prob. Just throwing stuff out there that I can think of.

 

[cheatham2492]

Re: Idle and Lean issue

Some times If your fuel injectors become clogged or a failure in the fuel system will show up like that. Yes you are lean at 148.Turn up the fuel pressure and make sure every thing is working properly.Fuel pump thru injectors.
DC

 

[Sy#1991]

Re: Idle and Lean issue

I am going to drain out fuel in tank and replace pump. Thought there might be a warbrol pump in there already but there is only 1 way to be sure. Than I am going to put some fresh 100 oct in the tank.

 

[The Bronze]

What are your iac counts at idle?

 

[The Devils Own Chariot]

Re: Idle and Lean issue

Bad plugs can do that. Change your plugs and see if that helps. If its happening over and over it can be a bad tune or oil past the rings.