1G Sudden Jerk or Shake During Hard Acceleration

[NinjaClyde]

I will start by saying i have searched for similar problems and have done the fixes for those problems and it hasn't fixed my issue.

I recently got a 90 Eagle Talon Tsi AWD and for the first week or so of having it i drove it fairly regularly. Recently i went to go overtake someone and when i was accelerating the car made a sudden strong jerk. Later I tried to see it i could cause the issue again on purpose by doing some full throttle launches. First gear went though fine, but then it second and third gear it had this hard shake at about 4500 RPM. Maybe forth gear as well, but i didn't want to go that fast with what ever issue that my car may be having.

To help clarify this is not a gradual shaking like wheel balance or alignment. it is a sudden hard shake like if you where push starting a car in first gear, though i don't know how many of you people know what that is like, i didn't until recently when i had to help my brother.

I have already cleaned the MAF sensor, replaced the fuel and air filters, and checked the spark plugs, which looked fine and gaped properly. When it shudders there is not check engine lights flashing or anything. I think it might be something to do with the turbo letting go or something but i don't know if that would cause such a violent shake.

My car is basically completely stock, as in no aftermarket mods, just it has 130,000 so obviously a few parts have probably been replaced.

PS: I don't know if this is related to the issue but one out of about five times i start my car it has a hard time holding an idle.

SOLUTION: For those who may have the same issue. Once I installed a real boost gauge i saw it was boosting too high for a stock turbo set up. It was a fuel cut issue caused by the hose in not connected to my blow off valve so it wasn't releasing the pressure.

 

[Talondvr]

I would say to do a BLT no matter what (leaks are never good). Get New plugs (bpr6es) and New NGK wires (or similar) and i would bet the issue will be gone. A boost gauge is a good idea too. I just bought (couple months ago) a triple pod vent in black from MachV. Its not listed at the moment but this one is: Black vent panel gauge mount (89-94) or they have others. The triple pod one was prya removed (at least mine) because the outer gauges hit the sides of the dash when installed (the above one linked to looks about the same tho). I have a shallow gauge in one side and cut the inside of the dash on the other.

 

[NinjaClyde]

Ok I tried to make a boost leak tester, but I could not find a 2 1/2 inch coupling anywhere in my town. I was able to get a boost gauge though.

I installed the gauge, and when I went for a test drive I learned either my car is not as stock as I thought or my boost gauge is reading too high. It goes into vacuum properly and seems to read right. In second gear it doesn't lunge and the gauge reads properly at about 11 psi, but then in third gear the gauge reads up to about 18-20 psi and the car has the lunging issue.

So I may have a MBC, so I am getting a fuel cut. Or my gauge is reading too high which seems odd and unlikely. Does any one have a good picture of an installed mbc in a 1g dsm so i know where to look if there is one installed?

 

[CrawlinZX14]

Im going to guess your "Near" stock car has an aftermarket exhaust right? If so then fuel cut would be the likely issue. My car with the stock 14b on it was hitting cut bad because it would read (and still does) 20+ psi due to the wastegate no longer being the path of least resistance. So as it builds boost it spikes hard. 22psi on my gauge, then gradually comes down to about 18-20psi. And this is without a boost controller hooked up at all. Strait plumbed from the compressor to the waste gate.

My fix was having my eprom chipped. I added other things in there with my chipping, but the chip solved the fuel cut issue. And for those, no im not hitting knock either.

 

[Jazz]

Follow the vacuum line that's connected to the wastegate. If u have a mbc it should be connected to that line

 

[NinjaClyde]

I feel stupid, the vacuum line wasn't connected to the wastegate at all, so it was getting extra boost untill it hit fuel cut.

 

[Blue Talon Boy]

That could explain it... Glad you got your problem fixed.

Sent from my ADR6300 using Tapatalk

 

[Cool canada40]

I will start by saying i have searched for similar problems and have done the fixes for those problems and it hasn't fixed my issue.

I recently got a 90 Eagle Talon Tsi AWD and for the first week or so of having it i drove it fairly regularly. Recently i went to go overtake someone and when i was accelerating the car made a sudden strong jerk. Later I tried to see it i could cause the issue again on purpose by doing some full throttle launches. First gear went though fine, but then it second and third gear it had this hard shake at about 4500 RPM. Maybe forth gear as well, but i didn't want to go that fast with what ever issue that my car may be having.

To help clarify this is not a gradual shaking like wheel balance or alignment. it is a sudden hard shake like if you where push starting a car in first gear, though i don't know how many of you people know what that is like, i didn't until recently when i had to help my brother.

I have already cleaned the MAF sensor, replaced the fuel and air filters, and checked the spark plugs, which looked fine and gaped properly. When it shudders there is not check engine lights flashing or anything. I think it might be something to do with the turbo letting go or something but i don't know if that would cause such a violent shake.

My car is basically completely stock, as in no aftermarket mods, just it has 130,000 so obviously a few parts have probably been replaced.

PS: I don't know if this is related to the issue but one out of about five times i start my car it has a hard time holding an idle.

SOLUTION: For those who may have the same issue. Once I installed a real boost gauge i saw it was boosting too high for a stock turbo set up. It was a fuel cut issue caused by the hose in not connected to my blow off valve so it wasn't releasing the pressure.

Ok so I had the jerk issue and mine was injectors where leaking air it wasn't sealed properly so if you guys have problem and you couldn't find the problem make sure you check your injectors