seafoam causing stumbling?!

[comsoldier20]

I put a whole can of seafoam in my gas tank. I only had a quarter tank (1/4) of gas left. about 20 minutes later on the highway my car started bucking. seemed like it didnt want to get over 4k rpms. also seemed to be more prevalent when I started to pass 0psi (getting into boost). car idles just fine and revs up to 2-3k just fine. all of my spark plugs are black (not the normal tan / cardboard color) when I hold my foot to the floor It will rev up to 4k then bounce around (sounds kind of like launch control )

My mechanical timing is fine and I don't have a check engine light. is my fuel mixture screwed up due to the seafoam?

 

[pearl4gtsi]

If I remember correctly, a can of seafoam treats a whole tank.... I would think if you dump it into a 1/4 tank, it'd be similar to using a 1:20 fuel/oil mix in a machine that needs a 1:50 mix. It'll run poorly.

 

[comsoldier20]

just went to and started the car again. exhaust does smell weird. idles just fine. as soon as a slam the pedal to the floor it starts chuggin. if I lightly press the gas pedal I can get it up to around 4k before it starts. I unplugged my MAF (before turbo) and the car started to run alot rougher. I assume the MAF is still working. I highly doubt a boost leak, all of my couplers are tight. and my BOV is spraying a bunch of air in my face when I rev it up.

 

[gusu]

just went to and started the car again. exhaust does smell weird. idles just fine. as soon as a slam the pedal to the floor it starts chuggin. if I lightly press the gas pedal I can get it up to around 4k before it starts. I unplugged my MAF (before turbo) and the car started to run alot rougher. I assume the MAF is still working. I highly doubt a boost leak, all of my couplers are tight. and my BOV is spraying a bunch of air in my face when I rev it up.

I would personally add more gas and dilute the mixture a bit more.

 

[Dsmkauai]

So is your bov vented or recirculated? Also if its blowing air out while revving than the eBay bov ain't doing its job. I would check out the vac line and also check adjustment of bov. I've never in my 16 years of being a tech had a problem with using seafoam, so I don't think it's really your problem. But you did over do it alittle on the mix ratio, how many miles on your car/engine. It's possible you lossend up some crud and clogged a injector or fouled a spark plug.

 

[comsoldier20]

my BOV does not recirculate (not my doing) when I rev the engine up and snap the throttle closed (doing this under the hood) the BOV opens and releases air. It seems to be functioning properly, it stays closed untill the throttle is released. all of my spark plugs are black but working, I have unplugged each injector connector while the car has been idling and the idle drops significantly indicating that I don't have a dead cylinder. I am going to add a few more gallons of gas to help dilute the mixture.

 

[Dsmkauai]

Ok well if your running a stock maf its highly recommended to recirculate the bov like the stock one is. If your plugs are all black than your running rich, that could be from many things. The bov not being recirculated will cause richness in between shifts, a clogged injector can actually drip to much fuel instead of a nice spray when clogged. When's the last time you changed the plugs on that thing. I wouldn't rule out a fouled plug after adding that much seafoam. Anyway let us know how else we can help.

 

[johnmel]

Fill the tank and see if the problem stays

 

[comsoldier20]

update: Added about 3 gallons of fuel to the tank. fuel gauge is reading half of a tank. I pulled the plugs and sprayed the tips with carb cleaner and reinstalled them. there is no change. car will idle just fine, but as soon as I slam the peddle to the floor from idle it just chuggs up to 2k. and bounces around. boost gauge typically reads 0psi when the stumbling is happening. It sounds like only 2 cylinders are firing during the stumbling. wondering if my TPS is bad.

My wires are about 2 weeks new and so are my plugs. got NGKs. car ran and boosted fine untill I downshifted into third on the highway. my next step is a compression test. I will also switch transistor packs, and regap my plugs to .28 to see if I get any changes.

 

[ErikTande]

If I remember correctly, the instructions on bottle of SeaFoam say to use 1/3 of a bottle in a full take of gas.

 

[nitewolf26]

I would check plugs, fuel filter since you practically cleaned out the gunk from the fuel system and it might have clogged the filter and dirtied plugs.

 

[Dsmkauai]

Do a boost leak test, you could have blown a coupler or something when you downshifted hard, makes sense to me. Also if it seems like 2 cylinders arnt firing right you could have fouled the plugs with the amount of seafoam you used its happen to many others on this site. Cleaning them with carb cleaner won't fix them being fouled.

 

[comsoldier20]

I put in 4 new spark plugs and gapped them to .28 I did a compression test and oddly enough I am getting between 195 to 200 in each cylinder. 2 weeks ago I had between 175 to 180 in each cylinder. Im wondering if mechanical timing can cause an increase in compression. My timing seems fine though.
I also swapped out coil packs and ignition transistor.

problem is still there, I cannot get over 0 psi and it stumbles up to around 3k. When I unplug this sensor (picture) there is no change in anything. are these sensors known to go bad?

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[Dsmkauai]

Sounds like you have a boost leak bro I would do a blt before going any further. Also check the tubro for excessive shaft play. The sensor in the pic is the mdp sensor or manifold diff pressure, its pretty much a useless sensor and shouldn't really effect anything, if it was bad it would probably throw a cel.

 

[comsoldier20]

thanks, I'm going to build a boost leak tester tomorrow.