My trouble tips

[clint78z]

I fixed my vehicle whohoo I thought it was poor tuning on my Accel DFI, nope it was good old fashioned trouble shooting that fixed it. I am now quite good at troubleshooting engines.

 

First check the igntion system first it is the easiest to eliminate. Get out the multimeter check 12v at the battery, next 12v at the coil and ignition module. Replace cap that's always cheap. Run up on TDC and check rotor postion, then firing order and plug wiring. Check timing, wire resistance, and then spark at plugs. There is a cool $5 part that hooks inline with spark plug that lights up when firing. Your ignition system is done.

 

Now it is down to Air/Fuel I had problems in both. Here is a good place to start with EFI, take the injector plugs off one at a time and get somone to watch the Tachometer. Each cylinder should drop the rpm by the same. In my case I found 2 cylinders that had no effect on rpm. Right away I knew the problem was with those 2 cylinders, either it wasn't getting proper fuel or a vacuum leak. If all cylinders drop equal rpm you either have a vacuum leak to all cylinders or fuel ratio is not right to all cylinders (sensor, computer, wiring, fuel pump...)

 

So after installing 2 new injectors boom car runs awsome.

 

START WITH THE EASY STUFF AND CROSS THINGS OFF ONE BY ONE.

[Guest gprix1]

I'm curious what your symtoms were. Was it all-around running poorly, just at idle? Just curious since you described the how you found the problem.

[clint78z]

Well I jumped in full bore rebuilt motor, new engine managment,different igntion system, turbo, injector upgrade, fuel pump. There were so many unknowns for me.

 

I thought I had the concept of tuning the DFI down, it ran real bad on first startup after all the upgrades. Problems Chev igntion module not grounded properly. Then some sorting of the fuel maps it ran decent and still started awsome, it had a minor miss in the idle, and poor responsiveness. The motor had poor engine vacuum. I made sure the injectors were sealing properly hissing noise was gone. Funny because the injectors were clicking but no fuel. I used a near by injector connection to verify it wasn't just the terminal end on the harness. When I put a known good plug on the injector no change in rpm, VOILA it's got to be a bad injector. Expensive diagnosis tools aren't nessary if you use a bit of ingenuity, and a good manual helps too.

 

Currently idles very smoothly, I get a bit of a flutter at 4psi and up, so I need to tune some more on the upper end of the map. A little passenger seat time with the laptop should hopefulley cure that.