Rep Power: 812

Okay here's what happened. I got an aem cam gear due to my head being milled. Most people here said I should advance it, so first day I turned it 2 degrees advanced. The car was starting very fast like turbo mode (good) and low end seemed better. Drove for a week and then went to a dyno. They say it makes the most hp when 1.5 degree retarded with only a small torque loss. almost 10whp gain for 2wtq loss. I drove around, wow seems alot faster above 4k. Now two days later my car starts to have serious starting problems. It happens whenever the car is cold or after its been sitting at least an hour after driving. I go to start, the engine shakes and makes clunk noises like its gonna die, and I have to give it gas a few times before the idle goes back to normal. I have no clue what to do. I'm keeping it stock 0 degrees now and the idle problem is gone. But I still wanted to tune it. I guess I can't?? retarding causes problems, and advancing is gonna lose more hp.

 
Rep Power: 331

i bet your ecu went into limp mode and caused something to mess up your idle control. Or maybe the simple fact that you did retard it makes the car run funny at idle, do you know what your a/f sits at during idle?

 
Rep Power: 812

well yea the engine was shaking so bad the CEL finally came on. I'm thinking you're right but then I guess that means cam gear on d17 is useless. Now after putting back to 0 and resetting ecu, the idle is fine (altho car is slower again).

 
Rep Power: 812

oay i've been reading on other forums, and basically its a very bad idea to retard timing with a stock cam. As far as compensating for a resurfaced head, usually milling requires advancing the cam timing, which would explain why the engine started and idled better with 2 degree advance. I guess its staying at zero for now...unless someone can offer an explanation.

 
Rep Power: 297

the problem is probably is something to do with the fact that when you change your cam timing your cam postiion sensor is also out of whack. The stock ECU probably eventually sees that there is a bigger difference between the cam postion and crank postion sensors. On initial startup I think our ECU advances ignition timing a lil bit to aid in quicker start-up. The ECU is probably not adding enough timing on start-up to be safe. I might be totally wrong on this but I think I gotta be somewhere in the ballpark. Anyone know for sure??

 
Rep Power: 812

so is it a bad idea to play with timing on these cars? Would advancing it 1-2 degrees be okay?

 
Rep Power: 293

When i advanced the car felt like **** big time i remember i told you. I seriously think the cam gear is hard to use on this car. But you should keep it like that as long as it doesnt mess anything up

 
Rep Power: 812

advancing a turbo car is generally a bad idea. You're supposed to retard timing if anything. with mine, its a complete opposite. mine is already starting out retarded below stock due to milling. So I need to advance just to bring it back to stock. have you tried retarding yours to see what happens? i know, its stupid to change cam timing on a sohc car since its a tradeoff. But i just want something that works and gives a bit more power without compromising lo or hi end.

 
Rep Power: 297

What would be optimal is to degree the cam but it would prolly be near impossible in the car. It should have advanced the timing if anything but it may only have been minimal, less than a degree. How much did you take off the head??

 
Rep Power: 327

dont forget cam timing and ignition timing are 2 different things. And as 02fpcivic said idealy the cam should be degreed in. Im not sure if it would be possible in the car or not

 
Rep Power: 812

true. i think they said 1mm of material. and i thought it was advance 1 degree per .3mm shaved. Who knows. It runs just fine at 0 so maybe i'll keep it there. Oh off topic but i'm still getting that loud belt squeak. They tightened up the belts last time and it does it alot less, but on rainy days i still hear it sometimes. sounds so getto. any solution to that? i think i need to stop worrying about the car so much...

 
Rep Power: 812

btw summit sells a degree kit for the cam. i looked at it and decided i could never do it. but i think its possible.

 
Rep Power: 327

I've seen it done before but have never actualy done it myself

 
Rep Power: 327

DING post #2000! , do i get a watch or something now.... im waiting for balloons to fall from above and Ed mcman to show up at the door, but no luck so far

 
Rep Power: 413

All advancing and retarding your cam does is move the powerband higher or lower.

IMO it's a complete waste. Just as its mentioned, if you retard or advance it, the ECU will adjust for it. Hence your idle issue. I think you should give up on that gear. You've been struggling with it for like a year now.

 
Rep Power: 812

good advice, i'm gonna take it. only reason i got it was people scaring me saying the milled head throws off timing. but ecus these days...i'm sure its working it out. hey if i can throw all those mods at it and still have pretty good a/f and engine running well, thats great.

 
Rep Power: 297

1mm is quite a bit though. If it runs fine at zero I guess leave it there but I'd say your initial idea on retarding it a lil was probably correct in theory but maybe it didnt change it as much as you/I think.

Cam timing IS definetly different from ignition timing. However they are directly related because the ECU is reading the cam postition to base some of its figuring on, including ignition timing. The outer edge of the timing gear has a steel ring that the sensor picks up on, which moves independent from the center of the cam gear as its adjusted. This should mean that you are actually lying to the ECU on cam postition if you set the gear anywhere besides zero. If it wasnt a DIS ignition, the distributor would be driven off the end of cam.Therefore, you would be changing your ignition timing equally as much as cam timing in relation to how much you adjust the gear. ATTN noobies, this DOESNT mean you can use the cam gear to retard the ignition timing to run nitrous or boost. The computer still reads a crank angle sensor as well as a few others to base its primary functions on.

 
Rep Power: 812

i checked the dyno sheets again and advancing cam timing 2 degrees on a stock d17 does nothing for torque and only increases 1-3whp in the top end. So maybe its not a big deal after all. now dohc, yea big difference tuning the cam gears.