Well iv been trouble shooting my car for a while now so i figured id turn to the board for some help. the car seems to have a bad bucking issue at part acceleration and more crusing at any speed in any gear basically. i think i got it down to being a fuel issue, i recently put colder accel u groove header plugs in it and it seems to run worse. i was running hotter accell plugs, i have new msd wires a new pro-form distributor, and the coil is a stock 87 camaro coil(small HEI)

i have an HSR with 28lb ls1 injectors and it seems that my car is running lean but i wasnt sure, i had it at high 50's for fuel pressure and it ran alright but kinda bucked then i checked it again and it was down at 45psi, so i turned it up to approx 60psi and it ran really good no bucking at all...then after i parked it after a 5-10 minute drive i drove it the next day the buck was back. and the fuel pressure stayed the same(at idle). so im not sure if my stock pump is dying on me or if my injectors arent enough, or if possibly my fuel pressure is too high. if anyone has any idea please chime in.

 

Its tough to teach a teacher but ill give my $.02. Im still gonna stick with a ignition problem. I would try a new coil considering they arent high dollar.

You shouldnt be losing pressure like you stated though. I would make that my last option. Good Luck



Are you doing any dataligging?

 

no datalogging, but i tried checking everything, only code i have is for my CTS but i think it might be do to either a bad connection or not enough grounds to the motor.....not sure exactly tried trouble shooting that one for a while. but as for my problem, ill go buy an MSD coil or try a different one that i have laying around, see if that makes a difference, it seems like it doesnt do it at all when i floor it or are almost flooring it. so thats what makes me think its not that.

 

If the CTS isn't reading right, then the ECM thinks the motor is probably WAY cold and dumping tons of fuel in it. THe reason you don't see probs at WOT is the ECM isn't trying to run closed loop then. If it were me I'd fix the CTS before doing ANYTHING else.....

 

i drove the car today, and the buck was even worse, i ran the car for a while with a wire crossing the connector for my CTS and it ran alright just a little buck, but with it plugged into the sensor it threw an engine light(code 14) and code 15 but no engine light when i had the wire jumped across it. so i crossed it again today and it ran alot better but slight bucking so i think maybe thats the problem, i might have to run 2 new wires from the ECM or put another ground on the engine to make it work correctly.

 

well since i messed with new CTS sensors and checked for 5volts and there was i dont know what exactly the resistance should be, can i poke each side of the connector wires when the car is running and check the resistance across it to see if its too low/high? because i jumped it with a wire and it seemed to run alot better but not great. still the same bucking, but no popping....any clue?

 

I see you're not getting a ton of response.

For what it's worth, mine exhibited similar behaviors when one of my injectors went South.
Good luck!

 

had a set of cleaned and tested lt1 injectors, now i have brand new ls1 injectors. plus i tested unplugging one injector at a time and it did the same thing, so its all cylinders doing it.

 

i used the LS1 injectors... yanked them because i would always run rich no matter what i did to change that.. now i have stock LT1 injectors and they are awesome..

bucking, i had this problem.. found it to be the MAP sensor was not getting enough vacuum.

 

if you can burn a chip try disabling your knock sensor temporally to see if the bucking goes away. I had a similar problem and it was caused by false knock at around 1400 to 1800 rpm. KS would pick up the false knock pull tons of timing and then engine would start bucking.

 

i dont burn my own chips but i had someone do one for me. iv sent it back to him thinking some of my other problems were because of the chip but it seemed not to change anything. i check the plugs after running the car, and they are white as can be.

 

I just cured a bucking problem (came on at 2500RPM) by swapping in a rebuilt distributor. I did a tune up (plugs, wires, fuel filter) and when I went to change the cap an rotor, my dist looked like hell underneath. I figured I'd start there. All cured.

Kevin

 

i had put new everything in my distributor, and i thought it could still be it, so i bought a new pro-form distributor and its no different. im thinking its the computer since everything literally is new on the car.

 

I did change my computer too. It was reading high temps even at startup and thus always lean. The computer was shot. I was sure that would cure it. It ran better (the car ran fine up to 2500) but didn't cure it the bucking. The distributor sealed the deal. Sorry, I couldn't be more help. Good luck.

Kevin

 

Well i tried out a used computer from a different car and it made no difference, i unhooked the battery, changed the ECU and the chip i left the same. well it ran really really good for about 1 minute then after i slowed down a few times it ran like crap again. so i went back and i figured id try a stock chip in it, well, it ran perfect. but i got a check engine light and then it would go away and it seemed like the timing changes and the light goes away, and i checked the codes and i get 33 which is low voltage at the MAF sensor. is it reading low because of my cam? 509/528 then w/1.6 rockers 543/562 222/230 duration and i also thought this would make problems with having no EGR or CS?

 

also do stock 86-87 165 ECU's have a rev limiter /fuel cut off? because i was racing my buddys car tonight and i was at abou 5500rpm in 4th @almost 140 and it cut off. im not sure if this was a fuel cut off or other related problem?