Car pulses under acceleration not a stumble, and sounds like a STI

[John_GST]

Ok here is the story, My GST has been sitting for a about 2 weeks now since I bought another one to drive back and forth to work. About three days ago I was going to drive it out to the store just to give it some attention, everything was fine until I pulled off my road and on too the high way. In between shifts the car fell very low in idle and would almost die before I could shift to the next gear, almost if I had the BOv venting to atmosphere. So I pulled over and check everything I could think of (fluid, oil, spark plugs, intercooler pipes, etc.). So I just decide to take it back home and as I turn on my road as soon as I got on the gas I heard a clunk sound. I didn't think much of it at the time I just wanted to get it back to the house.

Yesterday I go to start the car up and it starts fine with a regular steady idle around 750-800. So I figure that maybe it was just a momentary thing, and I leave to run to the grocery store. As soon as I pull out of my road I notice that something doesn't seem right the car was pulling fine and shifting fine but it seemed to have a pulse with the revs. I drive down the road debating what it could be and just have no clue. I pulled over and even with the clutch in it still makes the pulsing sound when the revs go up and you can somewhat feel it while driving. It sounds like a WRX STI when you start to build revs and its never done this before.

Can anyone please help me with this?
Thanks,
John_GST


96 Eclipse GST-----white
Mod list:
small 16g
Greddy type S recirculated
Greddy FMIC
Ebay Injen style intake pipe w/ cone filter

 

[Enraged78]

I've seen this happen twice.

The first time was when I did a 1G head/CAS swap on a 2G block with DSMLink. I forgot to check the don't look for misfire option in DSMLink and the ECU detected (incorrectly) a misfire. The ECU stops firing to one of the coils and you get an engine that sounds an awful lot like a flat four, or a WRX.

The second time I saw this was when a customer's car had an ignitor that was crapping out. Results were the same. The coil for 1&3 stopped firing and the car sounded like a flat four again. Replaced the ignitor, problem went away.

Do you have a check engine light? Sounds like you have some kind of misfire.

Matt.

 

[T9S1i]

Yes, i would vote for a misfire as well...
Check to make sure all your plug wires are on correctly, and all ignition components are plugged in. IF they are all good, then i would start checking the specs on them and replacing accordingly.

I had a slight misfire in my car when i was running methanol, i thought it was my alternator going out, i replaced the alternator, went out for a drive, the car felt better and when i went to do a pull...misfire happened again, knock sensor didnt show knock, and kaboom, i put the #1 rod through the block. It ended up being my coil was going out, and i didnt know (obviously).
Moral of the story... Fix your small ignition related misfire problem before you drive your car again/do pulls in your car.

 

[John_GST]

Ok that was an idea that I have been thinking about, that it was a missfire and Im glad to hear that you all think it is too. Whenever I get a day off from work I will look into it Im off Thursday and sunday so maybe one of those days I can get into it.
Thanks for the help,
John

 

[John_GST]

Do you have a check engine light? Sounds like you have some kind of misfire.

Matt.

Yeah the check engine light has been there since I disconnected the stock boost solenoid.

 

[Enraged78]

Yeah the check engine light has been there since I disconnected the stock boost solenoid.

You don't have to completely remove the boost control solenoid when you remove the vacuum lines to the turbo. You can just bypass it and leave it plugged in so you won't get a check engine light. That way, if the ECU ever needs to let you know something else is wrong, you'll have an idea. Also, do you have a datalogger, or at least an OBD-2 reader? It will make things in the future much easier to diagnose. Or, you could get DSMLink and have the ability to tune your car, check codes, and eliminate check engine lights for some things.

Matt.

 

[John_GST]

You don't have to completely remove the boost control solenoid when you remove the vacuum lines to the turbo. You can just bypass it and leave it plugged in so you won't get a check engine light. That way, if the ECU ever needs to let you know something else is wrong, you'll have an idea. Also, do you have a datalogger, or at least an OBD-2 reader? It will make things in the future much easier to diagnose. Or, you could get DSMLink and have the ability to tune your car, check codes, and eliminate check engine lights for some things.

Matt.

I would like to get DSMlink but money is short right now. Thanks for the info

 

[John_GST]

Ok I finally got a couple days off from work now and I have my problem resolved and figured. What turned out was the mis-fire came from one of the spark plug wires had got cought in the timing belt and chewed it in half. So thats the thing and now its no big deal thanks for all the help and input.