Do any of you have off idle or part-throttle hesitation problems with these cams? Also, do any of you have a high compression motor with these cams?

I do and am trying to figure out whether it is due to the lack of low - end torque associated with the cams or some other problem. I know there are a dozen reasons that could cause this problem but I'd like to eliminate the cams as a cause.

Steve

I have an 11:1cr motor with c3 cams... I don't have any problems with hesitation, but I'm not sure exactly what you mean by hesitation either. Please describe what happens. Also, what other mods do you have & do you have the matching ecu?

Its pretty much what I said. When I initially accelerate from idle, the car will bog down if I don't rev it up to, say over 2000 rpms. Also it hesitates when shifting gears at lower rpms.

I've read several automotive books and did a pretty exhaustive search of the archives on this site, Nissanforums.com and SE-R.net to come up with a list of about ten different things to check. I've checked about a third of them so far and was going to start a separate thread if I still couldn't find the problem.

So far I've checked rotor, cap, and wires, read all my plugs (light brown/tan/gray), and attempted to find a vacuum leak. I haven't found any problems.

My relevant mods are 11.3:1 high compression, C2 cams, stock MAF, MSD 50 lb/hr injectors, JWT ECU for all this, Hotshot Gen 5 header, 2.5" custom exhaust all the way back (new cat and muffler), Fidanza flywheel, 300ZX fuel pump, 4-set underdrive pullies and Clutchnet clutch.

The injectors are used but they were sent to Marren Motorsports for balancing/cleaning, etc. and there were no problems. I'm assuming they are not the source.

I threw around the idea that the ECU was not programmed correctly but that will probably be the last resort. Also, if my clutch was slipping I wonder if that would give me these symptoms. The clutch only has around 3000 miles on it, however my JGY - built tranny re-developed 5th gear popout and then 1st/2nd gears took a shit so I was stuck in traffic and on a slight hill and all I could use was third gear. I remember smelling a lot of clutch then. I don't know how much damage that did.

Well, this has already started to turn into a separate thread but thats where I stand now. Any comments or help is appreciated. I'll update as I eliminate possible causes.

Steve

Originally posted by thepep
Its pretty much what I said. When I initially accelerate from idle, the car will bog down if I don't rev it up to, say over 2000 rpms. Also it hesitates when shifting gears at lower rpms.

I've read several automotive books and did a pretty exhaustive search of the archives on this site, Nissanforums.com and SE-R.net to come up with a list of about ten different things to check. I've checked about a third of them so far and was going to start a separate thread if I still couldn't find the problem.

So far I've checked rotor, cap, and wires, read all my plugs (light brown/tan/gray), and attempted to find a vacuum leak. I haven't found any problems.

My relevant mods are 11.3:1 high compression, C2 cams, stock MAF, MSD 50 lb/hr injectors, JWT ECU for all this, Hotshot Gen 5 header, 2.5" custom exhaust all the way back (new cat and muffler), Fidanza flywheel, 300ZX fuel pump, 4-set underdrive pullies and Clutchnet clutch.

The injectors are used but they were sent to Marren Motorsports for balancing/cleaning, etc. and there were no problems. I'm assuming they are not the source.

I threw around the idea that the ECU was not programmed correctly but that will probably be the last resort. Also, if my clutch was slipping I wonder if that would give me these symptoms. The clutch only has around 3000 miles on it, however my JGY - built tranny re-developed 5th gear popout and then 1st/2nd gears took a shit so I was stuck in traffic and on a slight hill and all I could use was third gear. I remember smelling a lot of clutch then. I don't know how much damage that did.

Well, this has already started to turn into a separate thread but thats where I stand now. Any comments or help is appreciated. I'll update as I eliminate possible causes.

Steve


My car does the same thing under 2k rpms, there is no power under 2k at all. I am pretty sure that is the norm, though. I don't think you have anything to worry about, but i would call JWT & DPR just to make triple sure. My car usually jumps around when it's in that area of the rpms, but I just fugure that's from lack of lowend power and a light flywheel with a hard enguaging clutch. Hope I could at least help a little. Good luck... Elea

What about a bad throttle position sensor. Have you tested it?

Originally posted by BORNGEARHEAD
What about a bad throttle position sensor. Have you tested it?

My Techtom shows 0.50 volts at idle. I haven't checked the voltage at WOT recently. The TPS unit is new though and was put on when I installed the new motor last Fall.

The throttle cable is also sufficiently tight.

Steve

why did you choose to use 50lb injectors anyways? thats way overkill and that could be contributing to the problem also. the quickest n/a hondas find that 370cc injectors are sufficient.

Originally posted by egg
why did you choose to use 50lb injectors anyways? thats way overkill and that could be contributing to the problem also. the quickest n/a hondas find that 370cc injectors are sufficient.

Good question. My high compression motor has been built to "hopefully" withstand a 100 shot of nitrous (with quench, Swain coatings, overkill cooling system). I haven't installed the kit yet but when I do I will be pushing close to 300 hp. That is why I went with the 50 lbers. Also, they were available for a great price at the time.

I thought about these injectors contributing to the hesitation but I know there are many other people who have these with our motors and don't have hesitation problems.

Steve

Maybe it is because the engine makes less torque down low? According to the SCC dyno test the C2s are losing like 15-20wtq below 3800rpm over stock 91 cams. Maybe the lag in acceleratiobn is due to the cams?

Originally posted by thepep
Do any of you have off idle or part-throttle hesitation problems with these cams? Also, do any of you have a high compression motor with these cams?

I do and am trying to figure out whether it is due to the lack of low - end torque associated with the cams or some other problem. I know there are a dozen reasons that could cause this problem but I'd like to eliminate the cams as a cause.

Steve

Are you using adjustable cam gears?
It's been my obsevation that SRs using C2/3 cams need their cam timing adjusted to maximize hp gains with the cams.

Originally posted by Nismo87SE
Maybe it is because the engine makes less torque down low? According to the SCC dyno test the C2s are losing like 15-20wtq below 3800rpm over stock 91 cams. Maybe the lag in acceleratiobn is due to the cams?

I thought about that possibility. Thats why I originally posted the question to other C2/C3 cam owners, to see if they are experiencing the same symptoms.

No, I do not have adjustable cam gears.

Steve

As a former owner of C3 cams, I can tell you this. JWT will adamantly stand by their statement of not needing cam gears and being able to run the cams straight up. This is not true. Try retarding the intake cam 2.5 degrees and advancing the exhaust cam 2.5 degrees.

I had the C2's with stock compression and didn't have any off idle hesitations. It did want to buck a bit trying to cruise at real low speeds like tooling through a car lot looking at new cars. I never messed with the cam timing at all and the car ran like a bat outa hell.