Hesitation under light throttle.

[mightbewrx]

Hi guys,
I started noticing a problem with my car this morning.
When I step lightly on the gas, my car hesitates to accelerate and the EGTs go up like crazy!!
The car was running fine last night.
Only change since then is I filled my tank with Amoco 93.
I have a manual boost controller set to 10 psi just to see if this problem goes away.
Does anyone has any suggestions?
It seems like a fuel related problem because the EGTs are going up so fast.

Any help will be appreciated.

Dennis

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[rexxer]

Vishnu noted this problem when their Stage 0 used a manual boost controller. Here is there solution, it describes the same symptoms.

http://www.vishnutuning.com/loadcontrol.htm

[Equilibrium Tuning]

when you say light throttle, how light and how much boost if any are you seeing during this hesitation? If you're under vacuum and its hesitating, I'd check the fuel pump, spark plugs, and fuel injectors. The EMI adapter is only supposed to fix hesitation due to high boost/PT situations and since you have your boost controller set to 10psi, I somewhat doubt that's the issue.

-- Ed

[pfhlipwrx]

Actually i have just been noticing this aswell. BUT only since it has gotten real hot here in Texas.....hmm...I'm not even on boost, just accelerating lightly...

[mightbewrx]

Originally posted by Vaus
when you say light throttle, how light and how much boost if any are you seeing during this hesitation? If you're under vacuum and its hesitating, I'd check the fuel pump, spark plugs, and fuel injectors. The EMI adapter is only supposed to fix hesitation due to high boost/PT situations and since you have your boost controller set to 10psi, I somewhat doubt that's the issue.

-- Ed

It happens mostly under very light to mid throtle and at low rpms. Boost levels never go past 10psi . I'm thinking I might need to replace my fuel filter. My car has over 25K miles. Is that something you would recommend?
I tried resetting the ECU, but that didn't help.


Thanks
Dennis

[Equilibrium Tuning]

fuel filter is another thing to look at for sure. Air filter as well.

-- Ed

[mightbewrx]

Update:
Reset the ECU and put back the stock ABC and still same thing. I've added some STP Fuel injector cleaner, and will see if that does anything later tonight.
Any tips/how to's on replacing the fuel filter? I looked at the manual and didn't find anything.

Thanks in advance
Dennis

[Austin]

Intake leak, post MAF sensor.

[mightbewrx]

Originally posted by Austin
Intake leak, post MAF sensor.

I have the stock Airbox with a K&N filter. Where would I look for this leak? Could it be a clogged up Air filter?

I'm doing these this Sunday:

- New air and fuel filter
- New spark plugs

Any other recommendations/tips?

Thanks
Dennis

[Austin]

Originally posted by mightbewrx
I have the stock Airbox with a K&N filter. Where would I look for this leak?

Look for the leak between the MAF filter (in the stock airbox) and the throttle plate.

Airbox to accordian piece, induction pipe, any nipples off the induction pipe, intercooler hoses, TB hose.

An air leak after the MAF allows unmetered air to enter the engine, making the computer deliver less fuel than you need for the amount of air you actually have, causing a lean condition. Not dangerous at light loads, but it causes bucking and driveability issues.

[mightbewrx]

Well, I took the car out for a drive on the freeway today, and now it won't boost over 7psi (after putting the ABC back on). I guess is running on limp mode.

Dennis

[Austin]

No, limp mode won't really allow any boost and you won't rev above 3500rpm.

You installed the factory boost control hoses incorrectly. You're running wastegate boost.

[mightbewrx]

Well,
I have one vacum hose going from the nipple on the turbo to a "T" connector. Then another hose from the "T" to the boost control solenoid, and another one from the wastegate actuator to the "T". Is that wrong??

Thanks
Dennis

[Austin]

Where is the restrictor?

[mightbewrx]

Do you mean the 3/16 adaptor? It's between the boost solenoid and the "T"(forgot to mention it).
I looked and didn't find any unplugged hoses, so I don't think I have it connected wrong.

Here is a diagram I made on how it's currently connected (excuse my painting skills)




Here is a picture I found on scoobymods that is simillar to my current install....





Thanks
Dennis

[Uncle Scotty]

NOT the 3/16" connector.

Inside one of the 'short' hoses attached to the 'T', there is a brass restrictor. It must be in the hose attached to the turbo outlet nipple.
Squeeze the hoses and one of the short ones should have a 'lump' in it. Attach this one to the turbo nipple.

[Austin]

Without that little restrictor from the compressor outlet nipple, there is too much air signal in the boost control lines for the solenoid to vent off - that causes you to run wastegate spring boost pressure.

[mightbewrx]

Originally posted by Uncle Scotty
NOT the 3/16" connector.

Inside one of the 'short' hoses attached to the 'T', there is a brass restrictor. It must be in the hose attached to the turbo outlet nipple.
Squeeze the hoses and one of the short ones should have a 'lump' in it. Attach this one to the turbo nipple.

Wow, thanks for that info, I didn't know that. I will try that tomorrow
Damn, what would one do with you guys!!!

Thanks again
Dennis

[mightbewrx]

Well, the hose with the restrictor was in fact attached to the turbo outlet nipple, but the hose was punctured. I had to cut a piece of it and was able to put it back on (made sure the restrictor was in there). Took the car for a ride, and still won't reach full boost. So I replaced the fuel filter. I haven't taken the car out for a ride yet with the new fuel filter in.

I also took all the plugs out and here is a picture...



I have gone to 3 different autopart stores and can't find the stock NGK plugs, so I was wondering if I definitaly need to replace the plugs. Otherwise I will have to go to the dealer and buy them.

Anyways, another question I had was, can I do a compression test with all the plugs out? Or should I pull them out one by one and do the compression test like that?

Next, I'm cleaning my K&N filter with the cleaning kit.

Thanks
Dennis

[mightbewrx]

Well,
Since I couldn't find new plugs anywhere today, I put the stockers back on, put everything back together and took the car for a ride. I'm happy to report that is back to full boost and no hessitation/high EGTs!!!! I'm so happy!! Looks like the filter was the culprit.

Thanks all for your advice...

Dennis

[Austin]

Originally posted by mightbewrx
Well,
Since I couldn't find new plugs anywhere today, I put the stockers back on, put everything back together and took the car for a ride. I'm happy to report that is back to full boost and no hessitation/high EGTs!!!! I'm so happy!! Looks like the filter was the culprit.

Thanks all for your advice...

Dennis

Sorry, the fuel filter was definitely not the culprit. There's no way for a clogged/fubar'd fuel filter to have any effect remotely like that.

[Equilibrium Tuning]

I would disagree. I had similar symptoms on my GTI VR6 and the fuel filter was indeed the culprit. A clogged fuel filter will cause the same lean condition as a vacuum leak like you suggested. With the car leaning out like that, you should be happy that it didn't make full boost. I'd still do a compression test for peice of mind.

-- Ed

[mightbewrx]

Originally posted by Austin
Sorry, the fuel filter was definitely not the culprit. There's no way for a clogged/fubar'd fuel filter to have any effect remotely like that.

Well,
That's the only thing I replaced, and I also cleaned the air filter. All hoses were connected, so there was no vacum leak.
I'm thinking it could've happend because before my last fill up, I ran the car with the "low fuel" indicator light ON for a while before refueling, so maybe dirt on the tank made its way to the fuel filter and clogged it up.
I'm just happy that is working fine now.

Thanks
Dennis

[KnightWRXRider_]

I've been having this problem too. Very jerky under low loads, at one point i had the gas pinned in 5th and the rpms weren't rising at all. I also got a CEL of P0122 Throttle position sensor circuit low input. Did you get that at all? Trying to figure out what's wrong with mine, it comes and goes.

Originally posted by mightbewrx


Well,
That's the only thing I replaced, and I also cleaned the air filter. All hoses were connected, so there was no vacum leak.
I'm thinking it could've happend because before my last fill up, I ran the car with the "low fuel" indicator light ON for a while before refueling, so maybe dirt on the tank made its way to the fuel filter and clogged it up.
I'm just happy that is working fine now.

Thanks
Dennis

[mightbewrx]

No CEL's.

This morning the problem resurfaced. Won't go over 7psi and jerky acceleration. Could it be a dirty MAF sensor?
I'm going to check the IC hoses, but from the outside they look tight.
This is pissing me off


Dennis