PDA

View Full Version : Surging at WOT


derek
08-21-2005, 10:20 PM
Hello,
I've been studing this website and reading your comments for about 8 months. I decided to ask directly about a problem, I'm currently having. When the gas pedal is mashed to the floor, it just surges back and forth until I back off the throttle, with clouds of black smoke coming out the exhaust. Does anybody have any idea where I should start to look to solve the problem?

Keller
08-22-2005, 11:29 AM
I'm a bit curious about the buildup, mileage, and condition of the vehicle.

Do you happen to have a scan tool? (My guess is no...)

Black smoke generally indicates a rich condition.

kenmosher
08-22-2005, 12:25 PM
Hmmm ... how much boost? Octane? Any pinging?

Could be a lot of things:

Overly rich (as Scott suggests)
Too much boost, inducing extreme retard
Too much fuel pressure
Weak ignition (plugs? wires? coil pack?)
Chip calibration
I would suggest turning the boost down to around 15 psi and starting from there and noting symptoms vs RPMs vs boost (from a reliable aftermarket gauge).

Also, check fuel pressure at the rail (with vacuum line off), plugs (gapped correctly? Good condition? No cracked insulators?), wires (might just replace them as a maintenance item), and fuel filter.

PaCemkr86
08-22-2005, 07:44 PM
is it stock?? need more info

derek
08-22-2005, 11:47 PM
heres some more info.The car is a 1987 grand national and was purchased last march 05 from the original owner(lady driven).Although she probably took it easy on the car she chose to drive it in winter and did not take good enough care of it.The odometer reads 80000 KM which is probably 180000 KM(X .62= roughly 112000 miles)She did have the motor rebuilt and gave me somewhat of a build sheet.Parts were from a company called Prentice enterprises in Ca. Invoice reads new pistons .020,rings,rods,mains,timing set,cam (probably stock),lifters,gasket kit(leaks oil,neoprene set going in this winter).020 reground crank,cam bearings,freeze plugs,oil pump,2 rebuilt rods,1 crane core?Unsure about the last 2 items.I started by making it roadworthy, springs,shocks,brakes(vaccum conversion)ball joints, sway bar links, re-core rad 4-row,billet vaccum block, 160 t-stat, IAC valve,alum mass air pipe.intercooler and turbo hose set,rebuilt MAF one sreen removed, home made cold air kit, 8" K&N filter, 009 42 lbs injectors,255 lph high flow fuel pump,hotwire kit, billet FP reg set at 42lbs vac off, stock headers welded between 3&5 and a bad one between 2&4,PTE TA49 turbo .60 A/R, new boost line with adjustable bleed off, 3" THDP, hi flow cat(not gutted) split to dual 2 1/2" pipes(mandrel bent),2 "turbo" mufflers,no tail pipes,new bosch O2 sensor,"Faze" 30lb boost/vac gauge. I unplugged the charcoal filter vaccum line for this gauge :nono: , air/fuel ratio gauge which is tapped into O2 sensor line and reads voltage with some blinking lights indicating lean or rich. oil pressure gauge,temp gauge .
I went for a spin tonight with the stock chip in the ECM and it ran a little better.Half throttle was encouraging .Full throttle brought slight hesitation .max boost was 20 lbs(probably too high)On the way home put in aftermarket chip (green alien head on it with #42 sticker)I was told it was a jay carter chip.It felt as though it made it more sluggish(rich?).When boost starts to come on my A/F gauge reads full rich.I was the guy who sent Ken Mosher the E-mail about the Turbolink cable problem.Incidentally my software is "turbolink v 4.0"but my cable is gray with ALDL at one end and paralell port at the other end (no ECM modulator) .the computers won,t talk to each other.I remembered some more stuff.New wires ,new plugs AC delco i,ll have to check the number and gap tomorrow.I did check coil tower resistance awhile ago.I can't remember resistance but do remember it was within spec.I have to get the turbolink up and running to get the info to solve this.Oh yeah also my tranny will only shift at higher rpm'sTV cable adjustment doesn't help.Tranny will be fixed but added it in case it's related somehow.

derek
08-27-2005, 09:03 PM
I just had a new crank sensor installed and what a difference! It really cleaned things up.The cam sensor is next,well adjustment anyways.

Keller
08-27-2005, 09:17 PM
Running 20# of boost is too much for pump gas.

Having the rich/lean sensor stuck onto the stock O2 is questionable. Might need its own O2. Might be disturbing the stock sensors readings to the ECM. That gauge should not be necessary with Turbolink.

Really should run both screens in the MAF.

derek
08-27-2005, 10:13 PM
I had considered that maybe the A/F meter is causing a problem with maybe some current draw that should be going to the ECM.I'm gonna dissconnect it and see. It seems like a bell and whistle item.Thanks for all the help too!