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LH 2.4 Fueling/Ping problems

vteckiller2000

vteckiller2000

300+ Member
300+ Club
Joined
Dec 3, 2010
Location
Iowa City
I have a 57 trim turbo on an LH 2.4 940 turbo.

I am running stock fuel pumps and injectors, stock base timing, straight exhaust.
New fuel filter
NGK BPR8ES plugs gapped at .022"
Known good 3 bar FPR

At any boost, when I tip into boost, the car goes lean, and gets to about 15:1 or leaner, then dithers back and forth a couple times to 12, 14, 13, then finally to the 11-12's where I want it to be in boost. After the initial lean spike is gone, and it is fattened up, it stays fat until I release the throttle, even after a couple of gear changes.

Predictably, the car pings badly, and I can feel a very large decrease in power.


My old LH 2.4 car did none of this, even with the lift pump on its way out.

I even tried my set of brown tops, and it does the same thing just as bad.


Any insight?
 
Sounds like you've got a MAF going a little haywire. I've had one that at onset of boost it would go from stoich to 12, back to 14-15, then back to 11-12. EVERY time. Never figured out why, but swapping in another one fixed it.
 
I am using the WB on its own. The stock o2 is still intact also.

I have two 016 AMM units, I'll try the other one and see if it helps.


I am also getting a 1-3-3 TPS code, but I am assuming it has something to do with the open air blow off valve. I ran out of welding wire, so I won't be able to make a recirculating intake pipe until tomorrow.
 
vteckiller2000 said:
I am also getting a 1-3-3 TPS code, but I am assuming it has something to do with the open air blow off valve. I ran out of welding wire, so I won't be able to make a recirculating intake pipe until tomorrow.
Click to expand...
:grrr: Should have said that code before! A dying TPS will do that for sure. Pretty much the way the ECU figures out how much fuel it needs is by using a combination of the MAF flowrate, throttle position, and O2 sensor feedback. If it thinks you're only giving it 25% throttle when you're really giving it 50%, it's going to initially calculate fuel for 25% throttle until it notices the MAF flowing 2x what it should be; in which case it richens it up a bit. Without a fully working TPS, you're not going anywhere fast. Though having an atmospheric BOV shouldn't matter since it happens when you hit boost, not when you let off. The BOV only opens when you let off.
 
faultywarrior said:
:grrr: Should have said that code before! A dying TPS will do that for sure. Pretty much the way the ECU figures out how much fuel it needs is by using a combination of the MAF flowrate, throttle position, and O2 sensor feedback. If it thinks you're only giving it 25% throttle when you're really giving it 50%, it's going to initially calculate fuel for 25% throttle until it notices the MAF flowing 2x what it should be; in which case it richens it up a bit. Without a fully working TPS, you're not going anywhere fast. Though having an atmospheric BOV shouldn't matter since it happens when you hit boost, not when you let off. The BOV only opens when you let off.
Click to expand...

It is not the TPS, I went round and round that sensor all day today. Tested, changed and changed again, same result. The TPS functions fine.

The TPS isn't even really a position sensor, but rather a switch. closed throttle closed the idle switch and WOT closes the switch for WOT. In between they are both open. Continuity checks out on all my TPS sensors.
 
Switching AMM made it worse. Now I'm at 14's AFR under full boost. Scary....

Now I have noticed even on light throttle tip in, it pegs my WB lean. Fuel pump?
 
vteckiller2000 said:
It is not the TPS, I went round and round that sensor all day today. Tested, changed and changed again, same result. The TPS functions fine.

The TPS isn't even really a position sensor, but rather a switch. closed throttle closed the idle switch and WOT closes the switch for WOT. In between they are both open. Continuity checks out on all my TPS sensors.
Click to expand...
Hmm, weird. I guess LH's idea of a TPS isn't quite the norm.:lol:

vteckiller2000 said:
Switching AMM made it worse. Now I'm at 14's AFR under full boost. Scary....

Now I have noticed even on light throttle tip in, it pegs my WB lean. Fuel pump?
Click to expand...
Could be. Check to see what your actual rail pressure is at idle.
 
Also, when I tried my brown tops, after sitting for only a couple of minutes, the rail was dry. No fuel came out when I pulled it...
 
fp relay, check valve on the pump, fuse....if the rail is dry, the car wont ****ing run
 
a t3/t4 is a big turbo for stock LH.

Larger injectors and letting things learn properly can go a long way to helping the tip in lean spot. This is known about LH larger injectors help a ton with the tip in lean spot, but chips can also help as they do adjust the fueling and spark timing for tip in when LH typically would run lean bone stock.


As said and seen AMM makes a huge difference, try more to see if any of them run different.

The TPS code because of a BOV goes away if you let LH learn properly.

And the TPS is just an on off switch, when the car is at idle (zero throttle opening) it is one way and then when the throttle is open it is the other. LH has NO idea how far the throttle is open once it is open, it just knows fully closed and open someplace between a little and all of the way.
 
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