<SOLVED> Stuttering

[daveismissing]

Thats a new Denso O2 sensor , co-incident with the new injectors in post whatever.
I don't think we saw any change. Try a third?

I put a large analogue meter on the TPS to check it, very smooth. Could change it for fun.

Drove the car a little at 49Lbs, still had stutters, possible less and disappeared faster- I need more driving to confirm. Want the video?

That's not an 8 thats a 4  smarten up Dave


 

[$1987 GN$]

I put a large analogue meter on the TPS to check it, very smooth. Could change it for fun.

You really need a scope to check it.

If this is all for fun why bother Steve, Ed etc?

AJ___

[ULYCYC]

On a cold start bring up the rpm's until it starts to miss. Shut off and pull all the sparkplugs. Report the condition.  I also assume you checked the plugs before all this happened and they are fairly new and correct.

[Steve Wood]

If you saw no dead spots, or places where the output was stationary for a small increment, then it seems okay.  If this is a new sensor and it did it prior, scrub that.

have you tried the egr as Ed suggested?  After that, remove the egr hose and plug it just in case the egr solenoid is leaking

[daveismissing]

I tried to manipulate the EGR, it seemed to move smoothly.
Pulling on the diaphragm made the car run worse.
It was likely cold when I did that, I'd likely remember if it was hot.

 

[ULYCYC]

It's suppose to run bad when you move it. That's good and should seal. Now how about the sparkplugs?

[gbsean]

I see TPS at .38....thought .42-.45 was for Idle

[Steve Wood]

I see TPS at .38....thought .42-.45 was for Idle

More like .36-.46

[daveismissing]

So I think I've pinned it down, whether by intelligent analysis or dumb luck? you can choose.

I was listening to the car on startup and thinking it sounded really good for the first few seconds.
Unplugged the cam sensor and the problem was not manifesting.

I've switched the sensor cap now and not had any stutter for a few days.

Now the fuel pressure is still up so I should bring that back down?

You guys were suspicious of the numbers, I'll try to get a logger once the budget allows.

[Steve Wood]

yeah, try bringing it down to where it should be.  A cam sensor can do things like that, but, usually, it keeps doing it...have to file this one away in my limited memory banks.

[ULYCYC]

Put the fuel pressure back to what your chip spec requires.  Then jump for joy if the new sensor cap fixed the problem. I doubt it but I've seen spells removed by witches that worked

[daveismissing]

I'm interested in the colored dots on the caps. I wonder i the mfg "binned" then according to some parameter- rise time etc.

[ULYCYC]

You line up the dots on the cam sensor cap with the red dot on the boost solenoid 

[daveismissing]

So BLMs are supposed to go up and down as you change fuel pressure?

[Steve Wood]

You might try reading some of this when you are bored.  http://www.vortexbuicks-etc.com/Scantool_Readings.htm

Dave's write up on blms is as good as I have seen. I link it on my page above, but here it is   http://www.gnttype.org/techarea/faq/BLMINT.html

When the ecm thinks the fueling is right for current conditions, it will read 128 on the blms.  If it thinks the car is on the lean side, it will add fuel and blms will rise showing that the ecm is adding fuel at that point.  Vice versa if it thinks rich and the blms will drop showing it is pulling fuel to get back to stoch.

If all things are even, if you add fuel, you would expect to see the blms drop...and vice versa.  The ecm does have learning capabilities so if all things remain constant, the blms may approach 128 with time.

remember that fuel FLOW changes by the square root of (new pressure/old pressure) so a five psi change is not a massive change.