4900 rpm break up... About to ram the car into a wall!

[TurboBuick86]

Hey all, ive been reading on here and searching on my current problem going on with the Buick. It seems that a certain amount of people on here can relate to similar things and i'd appreciate a updated answer if anyone has.

As for the car its on E85 w/ 80lb. injectors and a walbro 340 in-tank pump.

Ive narrowed it down that at 14 psi and under the car goes right the thru the entire rpm smooth. At anything more lets say 22-23 it pulls then passing 4,500 rpms it stops pulling and ends up sputtering at 4,900 rpms. I added a second Bosch in-line pump and the same thing is going on. I dont have a hood mounted fuel pressure line, can it be the walbro intank is messed up??

Ive tried another MAF sensor, Coil/Ign module, crank sensor, new spark plugs, even putting washers under the rocker shaft to see if it was preload and all these led to nothing changing. Maybe the ecm, chip got glitched somehow? its nicely secure in the stock location. Ive been at this for 72 hours and am running out of ideas... anyone plz give opinions. thanks

 

[imjoesnuffy]

If you dont have a way to monitor fuel pressure, your probably gonna be stuck until you do.

Hope you get it sorted out.

 

[bmackinnon]

Hey all, ive been reading on here and searching on my current problem going on with the Buick. It seems that a certain amount of people on here can relate to similar things and i'd appreciate a updated answer if anyone has.

As for the car its on E85 w/ 80lb. injectors and a walbro 340 in-tank pump.

Ive narrowed it down that at 14 psi and under the car goes right the thru the entire rpm smooth. At anything more lets say 22-23 it pulls then passing 4,500 rpms it stops pulling and ends up sputtering at 4,900 rpms. I added a second Bosch in-line pump and the same thing is going on. I dont have a hood mounted fuel pressure line, can it be the walbro intank is messed up??

Ive tried another MAF sensor, Coil/Ign module, crank sensor, new spark plugs, even putting washers under the rocker shaft to see if it was preload and all these led to nothing changing. Maybe the ecm, chip got glitched somehow? its nicely secure in the stock location. Ive been at this for 72 hours and am running out of ideas... anyone plz give opinions. thanks

Well.. your going to have to VERIFY the fuel pressure is rising 1:1 with boost, but it sounds more like an ignition problem... need scantool info... and the putting washers under the rockershafts?? _does_not_sound_good
Chips don't 'glitch'... if it runs good at 14 psi it's not the chip.. plug gap a tight .032? 'gimmick' plugs? what valve springs? stock? if it stops pulling at 4500, why rev it to 4900 to break it up? NEED_SCANTOOL_INFO_... 02's, maf, bl, int, KR, etc etc... a single walbro 340 pump is probably marginal on a built 80lb injected e85 motor...but with a 2nd inline pump... dunno... you need to get us more info... fuel pressure first!! unless you just love changing head gaskets...

 

[TurboBuRick]

What plugs? What gap?

Do you have access to another cam sensor cover? Try unplugging it while the car is running. Take it for a ride and see if it cleared it up.

Get the washer out from under the rocker shafts. I don't know where the hell you herd that from.

 

[Just a Six??]

Get the washer out from under the rocker shafts. I don't know where the hell you herd that from.

It's not all that uncommon. I have never tried it but many others have for various reasons. Crane & Comp actually sell them.

 

[TurboBuRick]

It's not all that uncommon. I have never tried it but many others have for various reasons. Crane & Comp actually sell them.

Hmm, learn something new everyday. Unless something with the valve-train or decking of some sort was done, makes no sense to me.

 

[incharge]

Close the spark plug gap to .020 with E-85 , if not check the coil pack with a ohm meter

 

[Just a Six??]

Hmm, learn something new everyday. Unless something with the valve-train or decking of some sort was done, makes no sense to me.

I believe it's do to deckheight, pushrod length & or geometry but I have never done it. I think (don't quote me) but Earl Brown & maybe Steve Wood mentioned as well as Ed Baker.

 

[SHADOWII]

Are you...

running your original valve springs? You haven't posted your sig. so all we can do is guess. Is there someone you can borrow a scan tool and fuel pressure gauge from? Maybe another board member close by that can loan or help you out?

 

[LOT]

Imo

plug wires

 

[TurboBuick86]

I have NGK ur6 gapped at .20. And it has a 206/206 comp cam with 100 lb springs. I'm buying a fuel pressure gauge this week and I haven't unplugged the cam sensor cap will be giving that a try as well

 

[QUIP'6']

subscribed

 

[Boost231]

plug wires

+1 thats what mine was

 

[bison]

Hmm, learn something new everyday. Unless something with the valve-train or decking of some sort was done, makes no sense to me.

It is used to correct valvetrain geometry not adjust the preload as he did it.

 

[bison]

If a/f is ok the instant it breaks up id look into the ignition. Plugs have been verified to be good. Ive had bad modules that cut out with high rpm but it wasnt load related like his is. Looks like a fuel delivery issue.

 

[TurboBuick86]

took off the vacuum line going to the adj. fuel pressure regulator earlier and got a air pump and the in hood gauge passes 100 when I pump air into it so it cant be either of the pumps of fpr. Im gonna unplug the cam sensor cap tomm and see what it does. Im running out of options, last resort I believe would be taking the cam out and degreeing it 4 degrees advanced.

 

[GNVYUS 1]

So you just added the hood mounted FP gauge and during a run it went from where to where (line off to WOT)?
Testing the gauge just tells us it's working, which is a start.

Like Bison mentioned, we need an AF/R to go off of.

Running a .020 gap is really tight, what's the coil 100k miles old?

 

[KL Mallender]

I have NGK ur6 gapped at .20. And it has a 206/206 comp cam with 100 lb springs. I'm buying a fuel pressure gauge this week and I haven't unplugged the cam sensor cap will be giving that a try as well

Valve springs.....valve Springs....pssst: valve springs........
Weak springs will make A/F mixture appear rich when float is incurred, if you lean it out to make readings look good...watch-out, that little extra boost is taking away a little effective spring pressure causing the difference. Or you could go ahead and lean it out which will help A/F look better but still lay down on power, then change springs and go out and floor-it with lean settings....Always a good time to observe from afar with head gaskets for sale :biggrin:
Good luck, and be careful

Kevin.

 

[thessman]

Valve springs here too.

 

[boostingbuick]

I've been there. I had changed every sensor and module. Then the cam was replaced. Even replaced the wire harness just to find out when we raised the boost with the alky the valve springs started to float. Replaced the springs and no more issue.