Problems after HG install. (lean codes)

[onspeed]

P0171 and P0174. Bank 1 & 2 lean. LTFTs are maxxed at +25% and the STFTs are ranging from 15-20%.

Just installed stock replacement heads on a suburban that's been sitting for a while. It's also throwing a P1345 code from the distributor not being set dead on. When I first started it a few days ago, it was throwing P1345 and a P0161 (pass. side post-cat O2 sensor). Today I changed the tranny fluid and swaped the rear O2s while I was down there to see if it was a cat or O2 issue. Started the car back up and it didn't throw anymore O2 codes, but the two lean codes. I sprayed some starter fluid around, and didn't find any obvious leaks. Around the front right of the intake, near the alternator, I think there is a tiny vac leak. RPM changed ~50 when I sprayed starter fluid. I tighted the plenum bolts there a little more but didn't make a difference and I don't know why the lower intake would be leaking. I used the metal felpro gaskets and ample RTV when I reinstalled, and torqued everything as per the service manual instructions... not sure if that minor leak would cause the car to run so rich though...

It has the stock fuel spider. Going to try changing the fuel filter tomorrow, can't remember if it's been changed recently. I've cleaned the MAF and changed the PCV valve. I also notice that when the car is warmed and I start it, it'll start and then promptly die. 2nd start is no problem though. However I'm not sure if the distributor has anything to do with that. Maybe the poppet valves on the stock spider are leaky and causing the engine to flood? It seems unusual that both banks would be bad, but who knows. Also sometimes there's a slight hesitation when moving from a stop. It lasts for a second, then it's fine. Reminds me of my C5 that has a lean spike when I'm shifting gears after a cold start...

I'd love some suggestions/comments. Car is a '97 k1500 suburban with 198k on the odometer.

 

[tscherbi]

P0171 and P0174. Bank 1 & 2 lean. LTFTs are maxxed at +25% and the STFTs are ranging from 15-20%.

I also notice that when the car is warmed and I start it, it'll start and then promptly die. 2nd start is no problem though.

Just a thought that pops to mind, possibly not relivant could this problem possible be because of a loos fuel line, or a rolled over o-ring on your fuel lines. Posibly causing a bleed off in pressure.

If it was me I would check your fuel pressure to start off.

 

[twomanymontes]

First, the truck's computer is causing it to dump fuel because it's seeing a lean condition, so the poppets are not the issue here. Never use starting fluid to detect vacuum leaks, that can cause major issues. Ever see valve covers explode?? I have. I always use brake clean, it seems to be less volatile and you can use the straw to get into places better. If you haven't found a external leak, you need to look for an internal one. With the PCV Vale pulled and plugged, see if there is vacuum from the valve cover. You may not have the correct intake gasket or it may not be seated properly and causing a leak in the valley.

Also check every vacuum connection as well as the upper plenum if you removed that. That D-ring around the injector housing can be easily damaged if it was forced on. I found that one out the hard way.

Your distributer needs to be reset to stop the P1345 code, if it's more than 16* off it sets that code. More than 8* it will run and start weird. You need to find a scan tool that reads the Cam Retard ID. Rev the engine over 1000 RPMs and read the ID, it should be 0, I usually set them at 2. If it's off, the distributer needs to be moved until it's at 0. The problem is the hold down doesn't allow much travel, Take the hold down of and grind the inside of it slightly so there is some adjustment room with the distributer. Then read the ID again. If it's way off, you might be a tooth off.

Hope this helps.

 

[onspeed]

Just a thought that pops to mind, possibly not relivant could this problem possible be because of a loos fuel line, or a rolled over o-ring on your fuel lines. Posibly causing a bleed off in pressure.

If it was me I would check your fuel pressure to start off.

Going to check fuel pressure that tomorrow as well.

First, the truck's computer is causing it to dump fuel because it's seeing a lean condition, so the poppets are not the issue here. Never use starting fluid to detect vacuum leaks, that can cause major issues. Ever see valve covers explode?? I have. I always use brake clean, it seems to be less volatile and you can use the straw to get into places better. If you haven't found a external leak, you need to look for an internal one. With the PCV Vale pulled and plugged, see if there is vacuum from the valve cover. You may not have the correct intake gasket or it may not be seated properly and causing a leak in the valley.

Also check every vacuum connection as well as the upper plenum if you removed that. That D-ring around the injector housing can be easily damaged if it was forced on. I found that one out the hard way.

Your distributer needs to be reset to stop the P1345 code, if it's more than 16* off it sets that code. More than 8* it will run and start weird. You need to find a scan tool that reads the Cam Retard ID. Rev the engine over 1000 RPMs and read the ID, it should be 0, I usually set them at 2. If it's off, the distributer needs to be moved until it's at 0. The problem is the hold down doesn't allow much travel, Take the hold down of and grind the inside of it slightly so there is some adjustment room with the distributer. Then read the ID again. If it's way off, you might be a tooth off.

Hope this helps.

I usually use brake cleaner or carb cleaner, but I didn't have any around so I was careful with the starter fluid. Had a fire extingusiher near by. You're right about volatility, the starter fluid is primarily diethyl ether, a common organic solvent (I'm a chemist), where as cleaners are usually methanol/ethanol based, which have a substantially higher flash point. But really you should use great caution when using either one in an engine bay. Both flash points are low enough (around -40C and 10C , repsectively) that even at room temperature (25C), a spark will cause a fire.

Now back to my car, I'll try checking for vaccum at the valve cover. Also will spray some stuff around the injector connector. You say the poppets aren't an issue. If something was clogged or the regulator was faulty, wouldn't that cause a lean condition and the computer would try to keep adding fuel until the O2s read normal?

And I'm going to bring the car to a shop to get the distributor set on Tuesday. Can't read the cam offset sensor with HPTuners unfortunately, and I don't know anyone with a Tech2 or EFILive. I don't think I'm off by a tooth, I installed it at TDC and the rotor was fairly lined up with the 8 marking.

edit- thinking about this some more. if it was actually dumping in loads of fuel, shouldn't I be able to smell a very rich exhaust? From fuel trim data, it's around +45% fuel from normal. Surely that would be noticible in the exhaust?

 

[twomanymontes]

Yes, I know using carb cleaner or brake clean is just as bed, Its just better controlled that's all.

And if you had clogged poppets or a faulty regulator, it could cause a lean condition and you may not smell fuel in the exhaust.

Can your tuner read the Short term Fuel trim? if so, a lean condition would read a + numbers due to the computer adding fuel. Try disconnecting a vacuum line like the power brake booster and see if the numbers stays +, then try spraying carb cleaner into the hose to force it rich and drive the numbers -. That will tell you if the computer is able to control the fuel trim.

 

[onspeed]

I can read fuel trims. I've got HPTuners, but it's only able to do basic OBD2 operations with the 96-97 trucks. No tuning or advance sensor readings (like the cam offset) because the PCM is apparently drastically different from the 98+ models.

the LTFT are both maxed at 25%, which sets the check engine light, and the STFT are around 15-20%, so it's adding a total of 40-45% fuel. I'll try your suggestion tomorrow as well.

 

[onspeed]

Changed filter and picked up fuel pressure gauge. i think the fuel spider is my problem. got 54 PSI at idle, drops to ~25psi within 5 minutes of turning off the car. Guess i'm in for a $300 replacement spider. At least I'll get the updated injector design.

 

[twomanymontes]

Before you drop money on the Spider injector, make sure you don't have a leak in the fuel line under the plenum. They do tend to crack and leak. But that won't cause a lean condition.

 

[onspeed]

There are no lines under the plenum... the fuel lines plug into the spider above the plenum. I don't see/smell any leaks throughout the system either.

Actually going to try changing just the regulator and see what happens. My thinking is that if a poppet valve is causing the pressure drop, then it must be leaking, which would cause a rich condition instead of a lean condition. A faulty regulator might cause my codes since the poppet valves rely on pressure to operate? It's a long shot IMO, since I feel like pressure issues would always cause a rich condition since it means fuel must be leaking somewhere...

Also managed to damage my fan. One of the blades broke off since I don't have the shroud installed and something dropped in and hit it. Just going to break off the opposite blade to balance it until I get a chance to find a used one.

 

[twomanymontes]

Yeah, Your right, I was thinking of a 4.3L motor. Sorry, My fault.

Good chance the regulator is stuck, The fuel pump creates the pressure, but the regulator will bleed pressure off.

Breaking the opposite blade may not balance it out, try running with it the way it is as see how it is. Too many blades missing will cause over heating