engine jerking, BOV? idk - Saab Forums

900SE · #1 02-26-2007, 01:19 AM

ok so I just put a Forge FMDV004 dump valve (partsforsaabs.com) on my '97 900 SE. I noticed that when i shift up and it builds up afull boost at the lower end of the gear the engine starts to jerk as it trys to accelerate. I first thought thatthe blow off valve i bought was junk and just dumping too early cuz it couldnt hold the boost. After a few of these jerking spasms the check engine light came on. Idk if that can be tied to puting on a BOV? I thought that was dumb because I didnt recall having any problems with my stock recirculation valve, so i put that back on figuring that was the problem. but nope, it kept jerking with the recirculation valve back on it too. i dunno if the problem can be tied to valves or if if the FMDV004 is reliable and will stay clamped? i have no idea what it could be?? does anyone know what it could be??

Roto · #2 02-26-2007, 12:08 PM

the forge DV is known to be a good unit. Any chance that there could be different springs available for it? By the way, are you sure that nothing became unhooked while you were putting it in? Any chance the vacuum line going to it is corroded? To me it sounds like it's not venting actually.

pat@forge · #3 02-26-2007, 01:11 PM

I have a few questions:
Do you have a boost gauge, and if so are your boost levels affected?
Can you hear either valve operate?
What code are you getting?

Roto · #4 02-26-2007, 08:41 PM

By the way if you don't know what code it is you can go to a place like autozone and get the codes pulled for free.

900SE · #5 02-27-2007, 12:14 AM

well i replaced the vacum line when i put on the blow off valve and yes i can hear both vlaves operatingso im starting to think that the problem may not be related to the valves/ boost/turbo components. Also i used my friends code reader and got a code "p0301" i think, cant really remember exactly what it was but anyways it translated into "1st cylinder misfiring" or something along those lines. So i'm pretty sure that means i just need new plugs hopefully. looking back in these forums i saw someone else had the same problem and the same car had these similar symptoms and i think it was his plugs too. anywaysi looked up thatNGK bcp7es-11 plugs will be compatable, butis there anything that's recomended for my car? what are the stock plugs and are there any brand i shouldn't throw in? havnt gotten that far yet. Also is there any chance that the blow off valve could havecaused this? i dont see how they could be related, possibly just a coincidence, cant remember the last tune up it had.

Roto · #6 02-27-2007, 12:35 AM

could be a coinsidence. These cars areREALLY sensitive to having the correct plugs. p0301 is infact a cylinder one misfire according to my chart. I believe the recommended plugs for your car are NGK-BCPR7ES gapped at exactly 0.39. The gap IS important on these cars. Also your owners manual would list the correct plug for your car.

If you don't mind I will move this thread to the our newest appropriate section.

900SE · #7 02-27-2007, 11:36 PM

sweet, thanks for the help, and thanx for that spark plug info roto

Roto · #8 02-27-2007, 11:45 PM

Not a problem. Usually if I don't know/have something I can at least point you in the right direction.

boostpowered · #9 11-26-2008, 01:17 PM

this happened to me #4 plug exploded went up a heat range and solved my problem

wannaBgroupB · #10 12-02-2008, 11:23 AM

Make sure when you pull the plug you check for oil residue. If the plug looks like it's got a lot of burned oil on it, or there's wet oil in the plugwell or on the piston top, you could have a leaking valve cover gasket. If that's the case, the new plug will justfoul again. It should be an easy fix if that's the problem (unless it's a blown piston ring, but vc gasket's more likely).

Of course, if there's no oil, then no problem

[[Just saw how old the original post was...Oops! Well, good advice nevertheless, no?]]