Factory Five Racing Forum banner

1 - 20 of 20 Posts

·
Registered
Joined
·
2,546 Posts
Discussion Starter #1
I have an anonying hesitation.It happens in 2nd,3rd,and 4th gear...If I am between 2000 to 3000 RPM and mat the go pedal there is a split second puase before it wants to do anything then it takes off as normal.If I roll into the throttle it will respond fine.Here's the combo 5.0 EFI,X cam,AFR 165 Heads,1.6 roller rockers,Cobra intake,70MM TB,24 lb injectors,24lb calibrated 73MM MAF,10 dgrees inital timing,but using a programmable computer to map the curve,.995 TPS voltage,40 PSI fuel pressure,new fuel filter,155 Walbro pump.Any ideas.


[ October 16, 2002, 06:06 PM: Message edited by: Smitty ]
 

·
Registered
Joined
·
2,546 Posts
Discussion Starter #4
Matt I'm getting about 4.6 VDC @ WOT.Although I havent seen the volts increase on an "O" scope the VOM dosent show any glitches.
 

·
Registered
Joined
·
916 Posts
My first thought is to bump the base timing to 14 deg., then check full advance @ 3k and confirm if going to 30 deg.
 

·
Registered
Joined
·
2,546 Posts
Discussion Starter #7
I have in fact tried a A9L,but it did'nt change the hesitation at all.Timing @ 3000 is 34.
 

·
Charter Member
Joined
·
36 Posts
Is there anyway to squirt more fuel in
(accerator pump)with your programmable
ECU? What kind are you using?

I am thinking it just needs a little more
fuel. Esp. if you have mapped the air
meter correctly.

[ October 17, 2002, 05:57 PM: Message edited by: MTcobra ]
 

·
Registered
Joined
·
2,546 Posts
Discussion Starter #9
Yes,I have increased fuel delievery throught out the curve until it was running waaay rich without a noticable change in the hesitation.Now the MAF meter is another question...it's a C & L and I've heard about plenty of people having problems with them,but I'm not sure if I'm experiencing the same type of symtoms.Maybe it's time to by a PRO M and see what happens.The ECU is a Speedbrain.
 

·
FFCobra Fanatic
Joined
·
2,510 Posts
I hope I'm not stating the obvious here but I had a similar problem. Come to find out my #3 and #4 pug wires had beed burned by the header and was shorting out intermittantly depending on wind flow and tourqing of the motor on acceleration.
 

·
Registered
Joined
·
2,546 Posts
Discussion Starter #11
With this problem nothing is obvious.Tuesday I pulled the plenum,valve covers,the cap and rotor.all the plug wires the plugs.Then checked all the
rockers for proper adjustment.When putting it all back together I had the opportunity to look at the plugs(alittle lean but not too bad)all the plug wires looked good(Ohmed out OK)for Motorsport 9 mm wires,cap and rotor looked good clean,dry,and no arc's,all the vacuum lines were fine,and no leaks at the lower manifold.Basically I didnt see anything wrong,but the hesitation continues.


[ October 17, 2002, 07:37 PM: Message edited by: Smitty ]
 

·
Registered
Joined
·
2,546 Posts
Discussion Starter #13
Phil if more tip in fuel is required I'm kinda scr#wed.I dont(think)have this capability with a Speedbrain,and the stock puter didnt make any difference.
 

·
FFCobra Fanatic
Joined
·
929 Posts
I don't think its tip in fuel if your tps is operating as you say. Pretty standard motor there (nice though) and many others don't have the hesitation. I might question egr. Is it hooked up? Matt
 

·
Registered
Joined
·
2,546 Posts
Discussion Starter #15
Yes EGR is intact,but I have not checked the voltage going to it lately.I did remove it,and clean it and the EGR passages in the intake,even though they werent that dirty.
 

·
FFCobra Craftsman
Joined
·
784 Posts
SMitty,

This is a fairly common problem with C&L meters. We can usually get it fixed with tip in fuel to clean up the lean spot in the curve. do you feel it miss at all when this happens or just fall on its face? If it falls on its face it is lean at that spot and try adding fuel in the curve there.

Phil
 

·
Registered
Joined
·
2,546 Posts
Discussion Starter #17
Phil with the Speedbrain I cant just add tip in,I've got to add fuel across the board for a given RPM (500 RPM increments).This I have done and havent seen any positive results.Do you think changing to another brand MAF would help.Do you think an increase in fuel pressure would help.Also today I'm going to try yet another A9L.


[ October 18, 2002, 09:03 AM: Message edited by: Smitty ]
 

·
Banned
Joined
·
5,303 Posts
i suggest looking at the motor running in the dark. some of my wires were arcing invisibly to the header through the boot, drove me crazy. the FMS blue wires suck BTW.

-james
 

·
FFCobra Craftsman
Joined
·
784 Posts
add fuel in the base table where it stumbles.
if you have close, part and WOT table then add to part and WOT table @ 2-3k and see what happens
 

·
Registered
Joined
·
2,546 Posts
Discussion Starter #20
The search is on for another A9l computer,cant seem to find one locally.In the mean time I increased fuel pressuse in 2 LB increments with no change.I also increased fuel in the fuel table from 2500 RPM up and still no change.I have to set up a remote fuel pressure gauge and see what is happening when the pedal gets matted.I'm starting to think either the Walbro 155 is'ent big enough,or after 6000 miles it's getting tired.


[ October 18, 2002, 08:49 PM: Message edited by: Smitty ]
 
1 - 20 of 20 Posts
Top