highway boost issue/engine code

[Xyloft]

My friend just bought a 99gst (who cant register because his email is hotmail) it has a turbo XS BOV, boost controller and K&N drop in filter. and thats about it. he just threw an engine code for "MAF reading above what is expected, still within limits.

heres the problem: in 4th and 5th gear on highway as soon as the boost gauge hits the top (stock gauge) the car jumps, rpms and boost fall, and then catch back on. there isnt really an idle issue, it idles very smooth though there is a slight bounce when he rev's it. I read in a couple other posts about the idle surge, there were similar symptoms, but it doesnt appear to be the answer.

he was told that the boost controller was set to 11 psi, (stock is 10psi?) how high will the OEM gauge read? i'm assuming that the gauge maxes out at a certain psi. (sorry for the n00b question)
the MAF is new.

how can we check to make sure the boost controller is installed properly. and the setting is right? not sure who makes the boost controller, it has blue anodizing on it and its manual. we have a greddy turbo timer, but its not installed.

 

[Meh987]

The stock boost gauge is not accurate at all. Tell your friend to buy an aftermarket one to read what the actual boost is. He could be boosting very high, like 18+psi. That issue on the highway could be fuel cut. This is when the computer tries to slow the car because the MAS is reading a lot of air.

 

[Xyloft]

my major concern is the boost controller or the BOV since i think neither were not installed professionally. I'm wondering if the boost controller is really installed correctly.

we havnt really checked for boost leaks, or any of the simpler issues it could be, if it was what you mentioned above (fuel cutout) how would he go about fixing it, without lowering his boost? like an ECU retune, or Piggy back fuel control unit?

thanks for the help so far.

we've already talked about getting a boost gauge. so hopefully he'll pick that up soon.

 

[Meh987]

I would not reccomend getting rid of fuel cut until you have at least an aftermarket boost gauge and a higher-flowing fuel pump. Fuel cut is designed to save the engine from running too lean and blowing up.

About getting rid of fuel cut, there are many piggyback fuel controllers. DSMLink can get rid of fuel cut. There's more, just search for them.

And about the boost controller, check this link and see if it's hooked up right. http://www.belitski.com/vfaqhallman.html

 

[Xyloft]

this may sound kind of stupid...wouldn't cutting the fuel make it run lean?

from the little i've read so far, i'm pretty sure the problem is the aftermarket parts are installed wrong. its either leaking or the boost isnt right. or the BOV isn't set right. the parts were all installed by the previous owner who i didnt meet so i'm not sure how good of a mechanic he was.

the boost conrtoller is supposedly set at 11psi (what the previous owner told us). so if we are hitting the fuel cut, would that mean he's actually boosting higher than that? i would guess that the stock fuel pump could handle 1psi over the stock 10. but thats good to know.

thank you very much for the link, i sent it to him, we'll hopefully get this worked out this weekend.

and of course once we get that problem ironed out--its time for the fun part... modding it correctly.

 

[Meh987]

This problem could also be a boost leak, so I would check that, too.

Also, fuel cut is when no fuel is injected to slow the engine, so it feels like hitting a brick wall.

 

[stockmkt8r]

Just a thought, but is he recirculating the turbo XS bov? If not, he should do that...

 

[oldman]

1. Your friend must get a boost gauge now period, it's not really an option. The stock boost gauge doesn't max out, it does not measure pressure, it estimates it by using other variables.

2. The boost controller you're describing sounds like a turboxs mbc. Post a pic of how it's hooked up.

3. I agree with stock that the BOV is probably not recirculated since most turbo XS BOVs does not.

4. Boost leak test.

5. check plugs & wires.

 

[Xyloft]

Just a thought, but is he recirculating the turbo XS bov? If not, he should do that...

thanks for the suggestions, the more i have the more i'll be able to check out this weekend.

n00b question: where would i find information on how to recirculating the BOV. from what i can tell, (the 5minutes last week i looked in his engine bay) the bov was venting to the atmosphere.

I sent him instructions on how to install a boost controller and he says he tightened the screw all the way backin and everything looked to be installed correctly, which should put him at stock boost.

i'll bring my digi cam down and take some pics of his setup this weekend, if we get together.

my guess is the guy before us (cars only a week old mind you). didnt seal the intake with RTV or didnt let it set long enough or something.

 

[stockmkt8r]

1. If the BOV is recirculated, there should be a hose running back from the BOV to the intake pipe before the turbo.

2. You shouldn't tighten the BOV screw all the way down! This will force the BOV to only work under high PSI. Loosen it up buddy

good luck and let us know what happens

thanks for the suggestions, the more i have the more i'll be able to check out this weekend.

n00b question: where would i find information on how to recirculating the BOV. from what i can tell, (the 5minutes last week i looked in his engine bay) the bov was venting to the atmosphere.

I sent him instructions on how to install a boost controller and he says he tightened the screw all the way backin and everything looked to be installed correctly, which should put him at stock boost.

i'll bring my digi cam down and take some pics of his setup this weekend, if we get together.

my guess is the guy before us (cars only a week old mind you). didnt seal the intake with RTV or didnt let it set long enough or something.

 

[Xyloft]

1. If the BOV is recirculated, there should be a hose running back from the BOV to the intake pipe before the turbo.

2. You shouldn't tighten the BOV screw all the way down! This will force the BOV to only work under high PSI. Loosen it up buddy

good luck and let us know what happens

not sure what the BOV is set too...

the boost controller was what he tightened down to stock. he followed the install instructions on the link Meh987 posted

 

[Xyloft]

so yeah...i only looked in his engine bay for about 5 minutes like i said. becausei had a haunch the parts were installed wrong, i had my friend check all the seals.

guess what the previous owner used to seal the BOV...electrical tape....

words cannot describe how i feel about using electrical tape to seal a intake...so i'm guessing thats the problem. I wish I lived closer so i could actually see the car more often.

i have some high temp RTV that we are going to use to seal it up this weekend.

i'm glad i posted here though, my friend thought the turbo was blown and was going to take it to a dealership.

the boost leak doesnt explain the CEL though. MAF reading higher than expected. after we fix the boost leak i'll see how she runs and see if she throws a code.

thanks for the help so far. he still needs to get a boost gauge, so we can see how the boost controler is working out.

 

[Xyloft]

i was finnaly able to get under neath the hood to see what was up.

he turned the Boostcontroller all the way down and that got rid of the engine problems/CEL on the highway.

we fixed at least 2 boost leaks. tightened up the BOV, fixed a hose that was kinked, (thinknig it was the Idle control sensor since when we oppened it up it idled better)
we installed his turbo timer, except i dont think the speedo part is hooked up right. we also fixed the shifter since whoever put it together last time didnt hook it up right.

he's getting an AF gauge, oil Temp gauge and Boost gauge for a triple gauge pod this week, so we'll be putting that in on friday.

obviously the car is running so much better. and i've decided that whoever had the car before my friend was a moron, or he paid monkeys to work on his car.

hopefuly all the problems are ironed out.