Car is "shuttering" at 5 psi of boost

[RABID6]

Hello,

Recently, I decided to drive my Turbo Regal and get the fluids flowing. During the drive, I encountered a problem with the car. I'll try to explain it as best as possible so bare with me. Here's the problem; When I drive the car and gradually increase pressure on the gas pedal, I notice the car starts to "shutter" really badly. I notice that the boost builds and then relieves, builds then relieves, etc. etc... while the pedal is steadily making its way to the floor. If I hold the accelerator in a standard position without moving it and somewhat maintain 5 pounds of boost, the car keeps shuttering (doing the previous example when pedal is gradually increasing). This symptom has affected the way the car shifts as a result. My car now shifts at 4800 rpm from 1st to 2nd and then when I mash the pedal for a split second, the car redlines and doesn't seem to put all the power to the ground. It's almost as if the transmission is slipping, but its not. Sometimes during the drive the car will shift fine and pull hard when the vehicle is not "shuttering". When it shutters, it shifts like crap and I experience all the problems that I listed before. I hope this makes sense to you guys because it sure as hell doesn't make sense to me.

So, I've spoken to 3 people that are mechanics thus far. All the mechanics told me that it seems like its the ignition. I don't understand how it could be the ignition and how it affects the car's shifting. It feels like the transmission is slipping. So, I took the car to a transmission shop and took the guy for a drive. Even the transmission guy said that it's something with the ignition and that the transmission shifts fine. No problems there. It definately does not make sense to me. So anyway, based on everyone's observations, I replaced all the spark plugs and gapped them at 33. I bought a brand new coil pack and Ignition Module. I checked the plug wires and they were fine. I replaced the wastegate actuator with a brand new one. I take the car for a spin, and continue to have the same friggin problem I had before. It seems to run a little better but I think I'm trying to appease my subconscious. If anyone has experienced the same problem with their turbo regal, please help me and give some advice on what to do. I'm at a crossroad with this issue and frustrated. I want to have fun with the car again and not sell the damn thing. Thanks for all the help. Looking forward to talking to you soon.

 

[Danster]

Done any recent changes/mods, i.e. New Intercooler/Upgrade Turbo? Does the vehicle have any mods?

This will help us to point you in the right direction.

Dannyo

 

[hrhoward]

Try checking your MAF and fuel pressure with a known good gauge.

 

[RABID6]

Yes, the car has mods. JE Pistons, Bored .20, Comp Cam 208, Motor is balanced, TA 49 Turbo, Turbo Tweak Chip, Alky injection, Walboro fuel pump, 42.5 lb injectors, ESP Frontmount intercooler, LS1 MAF and translator.

I recently put the front mount intercooler on and it magnified the problem. I noticed that the car was shuttering before but nothing like what is happening now.

 

[notacarlo]

This may be silly,

is the wastegate hooked to the actuator? What is the condition of the lines feeding the wastegate system?

 

[RABID6]

I bypassed the wastegate solenoid and the lines look good. Thanks

 

[hrhoward]

How long was it sitting? Fresh gas or old? What kind of readings are you getting?

 

[RABID6]

The car was sitting for approximately 2 months. I would start it every week and I put new 100 octane fuel in it. As far as the readings, I don't have a scan tool as of yet and I'm not getting a "Check Engine Light" either.

 

[TurboDave]

Based soley on the description which is a little hard to follow, and not having any seat time with this problem, I'd be guessing at a couple things to look at.

Compressor surge (if these changes were made during the down time) there were a lot of them that could contribute to it.

or


MAF is failing or has failed.

RABID6
You mention talking to 3 mechanics. Well, IMHO, never take one of these cars to a "mechanic" unless that mechanic is intimately familiar with computer controlled turbo charged cars. If they're not turbo charging experts, or at least familiar with these particular cars, forget it

 

[Mark E.]

Do you have Direct Scan on the car? Even not in use, just the cable plugged in?

 

[ChavoLC2]

Compressor surge

Turbo Dave mentioned surge. How does your car act when you go straight to WOT? car was acting the same it would shutter/stutter at part throttle it would buck at 5psi -15psi, boost gauge was all over the place bouncing it was terrible, but if I just punched it at went to WOT no problem. Ended up putting a Tornado in the MAF pipe right in front of Turbo inlet , no stutter, no shutter,no weird tranny crap, no bucking at part throttle just nice linear throtttle response .. Thought it was ignition, wastegate etc,etc and after changing parts/ throwing money at it to no avail. Turned out it was surge like Turbo Dave mentioned...A member here RIP Bruce Plecan had years ago suggested that turbo surge could be fixed by putting a Tornado in the MAF pipe infact some Turbo manufactores actually machine anti-surge bullet holes in the larger turbo intakes to prevent the dreaded surge. If you have a 3" intake go and buy a 3" Tornado if it's surge it will go away right now.

 

[turbojd]

What holds the tornado in place if you run a 3" chrome maf pipe, or do you need stock maf hose?

 

[RABID6]

Turbo Dave,

In reference to the compressor surge and MAF Sensor, those items were not replaced during the down time. I checked the wheel in the turbo and everything was normal. There was no play in the shaft. The car has been running fine until I put the intercooler on. However, I did notice that the plugs were kind of black like its a rich condition. Thanks for the help

 

[RABID6]

ChavoLC2,

In reference to how the car acts when I go to WOT. If I mash the pedal to the floor from a stop, the tranny feels like it takes it but the car shutters and then the RPM's shoot to the moon. It acts almost as if the tranny is slipping but its not because when I ease into the throttle through all the shuttering and then floor it, the car pulls hard. This happens intermintedly. Hard to friggin explain. I might just video tape what its doing and submit it to the board if I can. Thanks for the insight.

 

[ChavoLC2]

MAF pipe

What holds the tornado in place if you run a 3" chrome maf pipe, or do you need stock maf hose?

Pardon me for not being clear. My MAF pipe is chrome also, I put the Tornado in the hose that connects MAF pipe to turbo inlet. Measured how far the turbo inlet sets into the hose t installed Tornado so that when hose is pushed back on to inlet the Tornado rests on the lip of the inlet. If your worried about it migrating put another hose clamp on the hose right over the Tornado and tighten it just enough so it holds it in place.

 

[ChavoLC2]

Turbo Dave,

I The car has been running fine until I put the intercooler on.

You probably have a intercooler hose that's not on properly, you probably have a leak. Check out all your connections that they're on and tight and no tears or holes , car will act like that with a leak, hope that's all it its. The same happend to me on another car when I put a Dut necked IC at a friends house it was gettin dark and I was hurrying to get home. well I didn't quite get a hose on right. Started home and it was stuttering, bucking when I'd give it gas. Hopefully that's all it is.

 

[kingots2004]

check fuel pressure

 

[TurboDave]

Just changing an intercooler can have the same results. Causing compressor surge that is.

 

[pacecarta]

i think the answer lies in the wastegate setup

i had this problem with a TA49 high boost actuator on my stock motor (duttneck , 3" maf tube , lt1 translator 3x9 kn air cleaner , rjc modifies boost ctrl ) , couldnt slowly accelerate into the 5-15 range like you would to pass on a rural road withourt it bucking , above 15psi fall was fine but then i look like a kid hotrodding and have to worry about traction on street tires . and below 15 it sounded like i had cylinders missing (again not cool)
I put stock turbo and wastegate back on and studder was gone ,then went to a te44 and it too was smooth as glass ,back to the 49 setup and shudder was back , i did have a different wastegate on the te44 due to housing differencence
replaced motor and went with the te44 and again had violent shuddering decided to pull the modified rjc boost valve i had off and it was a little better ,
changed to a cottons 3" external DP with a tial gate (got rid of stock wastegate) and no boost control just tuner hookup and now i can accelerate at any rate to any desired boost level and hold that psi and its absolutely dead smooth .
so without any changes like suggested to the inlet air i have my stock feeling driver back . i beleive the rjc may have had something to do with it and the old wastgate and large 1.5" mease puck which i didnt port match completely so the housings would fit other setups probably didnt help.

 

[Blazer406]

A directscan log would do wonders....

I had a problem similar... my battery cable was too close to the header on the pass side... add a broken drivers side mount from gassing on it... and it could rock over enough to short out the battery connection momentarily casuing a bucking....or miss... then when it would unshort... all was well. I found on my DS log... battery voltage would go to 0 for about 2-3 frames... then back to normal..... like to have never found that....

Oh.... does it still buck if you turn the alky kit completey off?

HTH