YamahaSHO Problem Found!!! **Updated with more Pics!!!**

[yamahaSHO]

With a lightweight flywheel like that you will get the engine to stall if you rev it up and let it try to check idle again, until the computer learns how the new flywheel works. My car still stalls although "very" rarely when I either do that or push the clutch in at speed coming to a stop. I think if you reset the idle speed correctly and drive it for a while you'll be all set with that. As for the rough running, I hope you figure it out and it sounds like you are on the right track.

The flywheel is not causing this problem. This is VERY rough running...

 

[thumpida]

ok this is just a shot int the dark, if it is running that rich shouldnt it be smoking considerably?perhaps itcould use a new fuel pressure regulator. a very stupid question is the fuel filter locatedon the fuel or fuel return line? i only ask becasue on my previous 2 vehichles it was on the return line which made no sense to me.

 

[AutoSHO]

Jason,

The Helms is wrong then.

28-32 PSI @ Idle
38-42 PSI W/ FPR Unplugged

 

[masho95]

The flywheel is not causing this problem. This is VERY rough running...

No, no, no. I wasn't suggesting that the flywheel was causing the car to run rough like that. I was just telling you that sometimes if you press the clutch in while at speed or if you rev it up at idle the car "will" stall sometimes, it's just a property of it.

 

[Bizzy]

The staged cams can cause some vibration as can the flywheel. From what I understand on the flywheel it's luck of the draw, some do and some don't.

You'll get it worked out Jason, hang in there. She's looking mighty fine! :thumbs_u:

 

[yamahaSHO]

Thanks for the help and support everyone!!

I canabalized some parts off of Tom's Bondoraunt SHO's today.... Swapped the CCRM and DIS, as well as cleaned the contacts on the plugs and wires.

No change came from the above...

Tom and I ran the codes again... I cannot remember exactly what codes as I do not have the paper with me... but I got two concerning the fuel pump.... I recently put in a (thought to be) 190lph pump.... Some say I might have received a 225lph pump instead. Tomorrow, I will use my fuel pressure gauge with a bleed off valve to lower the pressure at idle.... Hopefully something comes from this.... I have an extra pump off an 89 and an extra fuel regulater as well...

I relearned today that it has great power after 2500 rpm... had 3 people in the car and it put me back in my seat much more than I expected. Also raced another 95 SHO, ATX, and pulled in 3rd when I should have been in second...

Can't wait to get it fixed... I have set the stop screw on the TB to keep the idle up a tad so that it won't die on me....

Please, keep your suggestions coming!!!

 

[yamahaSHO]

No, no, no. I wasn't suggesting that the flywheel was causing the car to run rough like that. I was just telling you that sometimes if you press the clutch in while at speed or if you rev it up at idle the car "will" stall sometimes, it's just a property of it.

Never really heard of anyone else having this problem... I have driven another SHO with a Fidanza and it did not do it.

 

[IT-Purrrs]

Please list everything that you modded and that you took apart when you first had the problem, hopefully one of us can get something out of that.

Good luck.

 

[yamahaSHO]

Please list everything that you modded and that you took apart when you first had the problem, hopefully one of us can get something out of that.

Good luck.

Read the first post again.

 

[yamahaSHO]

Jason,

The Helms is wrong then.

28-32 PSI @ Idle
38-42 PSI W/ FPR Unplugged

Chris I really don't see how the manual is wrong...

Anyway, I hooked up my fuel pressure tester w/ the bleed off valve again. While the car was idling, I pressed the button and dropped the pressure, it did not change the rough idle. Also tried another fuel pressure regulator, fuel held the same pressures. I normally run around 43 PSI at idle and we dropped the fuel pressure to about 10 PSI w/ no change.

I am starting to think I got a bad grind on the cams, I will be taking them out tomorrow.

 

[SHOman24v]

get a digital caliper and measure the height of your cams, if they are within spec (if you have the spec)...well you know...no need to remove them

 

[yamahaSHO]

get a digital caliper and measure the height of your cams, if they are within spec (if you have the spec)...well you know...no need to remove them

I also have to take into account the lash caps and thicker shims needed, and lots not forget the duration that could be causing over lap. Cammed cars with lots of over lap run like crap at idle but great once they are really spinning, my car shows the same properties.

 

[Slo-Sho]

That which can be quickly ruled out using a vacuum gauge, as stated in my previous post.

 

[SHOman24v]

hmm...makes sence...is the gap between the bottom of the new cam lobe and the shim change when new cams are installed?

 

[yamahaSHO]

That which can be quickly ruled out using a vacuum gauge, as stated in my previous post.

Vacuum is good.

 

[yamahaSHO]

After more searching I came across this post from Mr. Fred Hurder
"I have Stage 2 cams in my track SHO. The powerband is moved up higher, like over 5000. From 5500-7500, the car screams, but the idle is "jittery". There is no stereotypical "womp womp womp" of a big cam, it's more along the lines of a poorly running SHO (like a plug miss, almost), until you clear 1500rpms. Low-end torque suffers.

For a mostly street-driven SHO, I'd recommend NOT going with the Stage 2's."

I believe I have stage 2 cams and it is not liking the lightweight flywheel. Going to reinstall the stock cams tomorrow, I have to pass emissions... If it were not for the exremely lopey idle, I would keep these cams, the power is AMAZING!

 

[SHOman24v]

uh oh... thats not gonna be fun

 

[philw349]

Damn I love your car

Ditto. It's beautiful

 

[Off Road SHO]

Jason,

The stage two cams, (if you indeed have them) shouldn't affect your emmisions that much.

I think I would check those back plug wires ( clean them off) before I would change those cams out.

Tom

 

[AutoSHO]

As far as emissions, it really depends on where they test. If they test anywhere near idle the car is gonna fail miserably with all the overlap those cams have. If they only test at 2500 rpm he might pass, but they're still gonna be a lot dirtier than the stock cams.

In my experience, a bad plug wire is more likely to expose itself under load than at idle... I learned that one the long, expensive, hard way.