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Boost problem! MAF????

pcaminos740

New member
Joined
Sep 21, 2015
Hello everyone!
I have a 740 turbo 1986, b230ft, lh2.2. It has some small improvements in terms of power such as IPD turbo cam, ecu chip, 2.5 exhaust, 14 psi boost, K & N cone filter, etc. etc. I think it would have around 200 hp.

It really became a very fun car to drive.

But I have a problem, when I accelerate it to 100% it makes a small "cut".
I removed the "Boost Pressure Over-Pressure Switch" under the dash, and it has improved, but still has that cut when I'm accelerating it to the maximum.

Do you think it's the MAF sensor?

Do some research on the web, and I found the following: "boost increases on the pre 1990 models should be combined with the 76mm MAF found on the 1991-1994 960s The standard MAF will max out on boost increases and lead to a cutting of fuel. "

I do not have any boost leak, the injectors (stock) work properly, the spark plugs and spark plug wires also. Everything seems to be working well.

What is your opinion? can it be the MAF? If that were the problem, which MAF should I use?

My english isnt very well, Hope you guys can understand me!

Thanks for the help!!
 
If it's sputtering at a certain threshold, you might have a boost cut in the lh2.2 system.

If so you'll either need the 3" maf from the 960 or plop the innards from the 2.5" maf into a 3" aluminum pipe. if it sputters at the same boost level each time, then it is probably the fuel cut kicking in. Look up the 3" MAF mod on the forums and don't forget to match the injectors.
 
If it's sputtering at a certain threshold, you might have a boost cut in the lh2.2 system.

If so you'll either need the 3" maf from the 960 or plop the innards from the 2.5" maf into a 3" aluminum pipe. if it sputters at the same boost level each time, then it is probably the fuel cut kicking in. Look up the 3" MAF mod on the forums and don't forget to match the injectors.

A 960 MAF will not work with lh2.2 I think...
 
I thought lh 2.2 was only the boost cut switch under the dash. I hit 14+ with mine and just the boost switch bypassed, and no cut or stutter. It must be something else. Airbox to turbo hose collapsing?
 
I thought lh 2.2 was only the boost cut switch under the dash. I hit 14+ with mine and just the boost switch bypassed, and no cut or stutter. It must be something else. Airbox to turbo hose collapsing?

MAF is probably going out of range from the volume of air coming in...
 
I ran brown top injectors on lh2.2 and made 209hp and 230ft/lbs. You have to adjust the maf quite a bit to get it to idle and cruise at a reasonable AFR. You may be running out of fuel. Or you can do the 3" maf and go even larger on the injectors but I think it needs 42lb/hr injectors to run properly, it will be way too lean with stock injectors. If you're interested in the brown tops or the 3" maf I have both I could sell you. I don't have the correct size injectors for the 3" maf though, just pm and I'll try to locate them in my parts collection.
 
thank you all for your answers and your interest in this problem.

I already have the over boost switch bypassed.

I also installed a wideband to control the mix, and is at perfect levels

When I started to improve the power of the car, I tried the green injectors (0280155968) and they did not work well.

My MAF can not be adjusted (I've seen that some can be adjusted by a screw, I think mine does not)
 
Also like masswrecker stated above the other thing that causes this problem which is common, happens a lot, is the intake hose before the turbo collapses and causes your motor to cut out like you describe when you floor it 100 percent. Check your turbo intake air hose make sure it is stiff and not soft and flimsy.
 
Also like masswrecker stated above the other thing that causes this problem which is common, happens a lot, is the intake hose before the turbo collapses and causes your motor to cut out like you describe when you floor it 100 percent. Check your turbo intake air hose make sure it is stiff and not soft and flimsy.

which of the hoses would it be? all have a maximum of 2 years of use (they were changed with the rebuild of the engine).
I put a link here with a photo with the numbered hoses

kZx7HR


https://ibb.co/kZx7HR
 
It should have the adjustable screw if it's a 007...

yes but it is a "blind" cap, I can not adjust anything :(
Although I can borrow from a friend who has the same MAF and I'm sure it can be adjusted. In that case, how should I adjust it? how many turns?
 
It's the air intake hose that hooks to the intake of the turbo and connects to the AMM. The hose from the air mass meter to the turbo. Think about it, the hose that hooks to the turbo intake of the turbo that the intake air for the motor runs through.

Before the turbo boosts the air it sucks the air, it sucks real hard when it boosts real hard and if that rubber hose is soft it squeezes it shut.
 
It's the air intake hose that hooks to the intake of the turbo and connects to the AMM. The hose from the air mass meter to the turbo. Think about it, the hose that hooks to the turbo intake of the turbo that the intake air for the motor runs through.

Before the turbo boosts the air it sucks the air, it sucks real hard when it boosts real hard and if that rubber hose is soft it squeezes it shut.

It is difficult for me to understand sometimes, because of the language and because I do not have much mechanical knowledge. But I think I understood what hose you mean.
I do not know what parameters to take to make sure it is stiff and not soft and flimsy. It is a hose that has barely 2 years of use, and I bought it again at that time.
What I can do? change it for a reinforced one?
 
It is difficult for me to understand sometimes, because of the language and because I do not have much mechanical knowledge. But I think I understood what hose you mean.
I do not know what parameters to take to make sure it is stiff and not soft and flimsy. It is a hose that has barely 2 years of use, and I bought it again at that time.
What I can do? change it for a reinforced one?

That hose:

fhWlRiY.jpg
 
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