Hey guys. I installed my ASP 25% UDP today and then on the way home the 'service engine' light came on. I went back to the shop and hooked up the computer and it said there was a random misfire on cyl 1 & cyl 5. We couldn't see anything wrong so we cleared the code and after driving about 50 miles it came back on again. The car still runs fine and I didn't feel a misfire. The computer said the same thing this time. Is there some thing about the UDP that might be doing this? I know it has the sensor ring on it and I'm thinking I might have to put my old ring on the new dampner. Has anyone else had this happen?

 

all ivebeen told to watch out on the udp is to watch the idle on autos cause it may cause it to stall depending on variables

 

I dont see how a smaller pulley could cause that, an accessory shouldnt cause any misfire to occur, even if the alt was off u should still be okay, i dont think its related

 

Not the pulley itself. The new udp has the balancer and a crank trigger ring on it already and I'm wondering if there could be some thing wrong with the crank trigger ring since it started right after I installed the udp.

 

aahhh forgot about that one, is it a reputable pulley or ebay crap???
if it is from ebay then yes, put the stocker back on if not, i dunno, it could b but i have never heard of it b4

 

Yeah is an ASP brand and got it from Stang Mods. It cost $250.00 so it should be better than the stock unit so it really pisses me off plus I have to re-do the whole thing and hope that's the problem. I did notice #1 & #5 are close together on the coil pack so it's possible this is a coincidence but it's too weird that it started right after installing the udp.

 

did you have a little heavier foot right after you installed it? if so you might not of gave the engine enough time to get used to it.

 

you can try putting the old pulley back on and see if the miss goes away. it is possible that the trigger ring is not on properly. if nothing else you can take the trigger off the stock crank pulley and try that instead of the one ASP sent you, as there may be a problem with that one.

 

I did a little on the first test drive but then later it threw the code and after clearing it I drove normal and it came up again. What would have to get used to it? The trigger ring and dampner are supposed to be the same size, it's only the pulley that's smaller.

 

That's what I'm thinking too, to use the old trigger but it sucks having to do this again. If that cures it it won't be too bad but it still gripes my butt after costing so much. I'm wondering if one or more of the teeth on the trigger are bent slightly, if that could cause this?