Fuel injection conversion, problems, popping.

[montegoman351]

I've got a 351 Cleveland, I converted to EFI last summer, but I've got one annoying problem!

From a dead stop, if I accelerate rapidly, it pops back through the intake.
If I get back in the throttle too quick, it pops back through the intake.
If I go WOT, it surges and pops back through the intake.
In park or neutral, I canquickly blip the throttle and it hesitates then revs.
If I smoothly accelerate, it does fine.

WTF is wrong.

I've pulled the codes and got all the stuff I don't have.
EGR, EVR, CANP, AIR, all the stuff I don't have.

I don't have rich or lean codes, but everything I've read points to "lean pop".

I have a new C&L 76MM mass air, yes it popped with the old one.
Adjustable FPR, I've tried to adjust it to give more fuel, still pops.
24lb/hr injectors, with 24lb sample tube.
New ign module, stator, etc. (recent engine rebuild, got new stuff)
Timing set at 8*, I've tried more and it still does it.
TPS set at .95, I've tried to move it both ways with no change in the popping.
70MM throttle body, did it with the old one too.
New intake gaskets, and such, still pops.
MOROSO Ultra 40 plug wires, popped with the FMS wires too (engine rebuild)
New ACT, ECT, O2 sensors, TP sensors. (all new sensors with conversion)


With the 19lbers, it would pop in park or neutral when I blip the throttle once or twice.
It seemed to pop more with the old 19lbers than the 24lbers, so I'm guessing it could it be a lean pop.

Any thoughts, do I need bigger injectors?
I've done the manifold a couple times what with the rebuild and a rear seal leak, both times I used new gaskets and it didn't change it.

I've got 2 bbl Cleveland heads with 2.07 intake 1.65 exhaust valves, ported and polished, factory 2 bbl intake with injector bungs welded in, custom-homemade billet adapter to adapt a '00 econoline upper TB plentum to the 2 bbl intake.

Here it is if it helps: http://www.cardomain.com/ride/2425255

I can't datalog, I wish I could, but I only get the codes for the extras I don't have.

Is it leanin' and causing preignition?

Any help would be greatly appreciated, Chris.

 

[montegoman351]

Oh, and I'll pull the plugs tomorrow to check the color.
Sorry for such a long post above, but I wanted to cover all the bases of stuff I've already done.

 

[ShortThrow50]

the only thing i can say is that 24 pound injectors are more than enough. almost sounds like your getting to much fuel which could be causing the pop

 

[vristang]

An EFI 351c!
Pretty cool!!!

What ecu did you use?
Does the MAS (the black MAF sensor) part number correspond to the original application of the ecu?
These must be matched with the C&L meter.


that's what comes to mind right off the bat...
jason

 

[montegoman351]

It's an A9P mustang computer. It seemed to pop worse with the 19lbers, making me think it was a fuel issue.

I'm probably pushing 350-400hp, haven't had it dynoed, I'm going by the desktop dyno to get an approximation.

The MAF sensor is one that goes to that computer.

I always thought too much fuel backfired in the exhaust because of the heat of the exhaust igniting the raw fuel. And a lean condition backfires into the intake because of preignition of not enough fuel.

It's an intake backfire, and boy is it embarassing.

Spintechs, x pipe, longtubes, 2 1/2" exhaust, and an intake backfire.

(isn't there a jingle about this) (oh yeah)
One of these things is not like the other. One of these things just does not belong.

 

[jrichker]

See http://www.pricemotorsport.com/ for an adapter plate to mate a 302 EFI intake to 2v Cleveland heads/cleveland block.

Backfiring out the intake is either a valve stuck open or a lean mixture or spark plug wire(s) connected to the wrong cylinder(s). Check compression on all cylinders and then look for vacuum hoses loose, cracked, or misconnected. Check the line for the vapor recirculation system – it is easy to knock loose and not see it when you connect the air pump plumbing. If the vacuum line for the EGR valve and the air pump are cross connected, some very strange things can happen. Check the mass air flow electrical connection and see that it is tight, the same goes for the fuel injection wiring harness connectors up on top of the manifold near the firewall.

Sticking valves: If a intake valve is bent, has a bad spring or is misadjusted, the engine will sometimes backfire through the intake. Use a vacuum gauge connected to any convenient spot on the intake manifold. Run the engine at 1000 RPM & look for 18-21 inches of vacuum with a steady needle. A problem intake valve will make the vacuum gauge needle sweep 5-10 inches.

Lean fuel mixture breaks out into several sub categories:
A.). Vacuum leaks
B.) Air entering the intake without passing through the MAF.
C.) Failure of the MAF, BAP/MAP (Baro or Manifold Air Pressure, same sensor, different name), ACT (air charge temp), or ECT (engine coolant temp). These should set a code in the computer.
D.) Leaking exhaust gases from EGR valve at WOT or EGR opening when it should not be open.
E.) Poor fuel delivery due to bad fuel pump, clogged filter or bad fuel pump wiring. Look for low pressure or fluctuating pressure. Standard injector pressure is 39 PSI at idle, with the vacuum line disconnected from the regulator and capped.
F.) Clogged fuel injectors.- see the cylinder balance test below
H.) Fuel injector wiring problems causing injector not to deliver rated flow.
I.) Computer problems: (computer problems are not common like sensor problems)
J.). ROM has bad data in fuel or timing table. This should also set a code in the computer.
K.) Failure of one or more of the computer's driver transistors for the fuel injectors. No code set on this one. Use a noid test light to test the injector wiring & injector drivers,
L.) MAF calibration off or mismatched to injectors.
M.) ACT or ECT bad. Sometimes the sensors will be off calibration, but not bad enough to set a code. If they falsely read too high a temp, the engine will back off fuel delivery.

Cylinder balance test:
Warm the car's engine up to normal operating temperature. Use a jumper wire or paper clip to put the computer into test mode. Start the engine and let it go through the normal diagnostic tests, then quickly press the throttle to the floor. The engine RPM should exceed 2500 RPM's for a brief second. The engine RPM's will increase to about 1450-1600 RPM and hold steady. The engine will shut off power to each injector, one at a time. When it has sequenced through all 8 injectors, it will flash 9 for everything OK, or the number of the failing cylinder such as 2 for cylinder #2. Quickly pressing the throttle again up to 2500 RPM’s will cause the test to re-run with smaller qualifying figures. Do it a third time, and if the same cylinder shows up, the cylinder is weak and isn’t putting out power like it should. See the Chilton’s Shop manual for the complete test procedure

 

[montegoman351]

Well, I messed with the timing and fuel pressure more, I set the timing to 12* and 60psi on the FP. The back fire has become less common and the bog is ALMOST gone, but still there. I got it to pop once under a full load, and in passing gear it bucks and jerks still.

I pulled a plug and it is paper white with a small spot of tan (not much).

Since I upped the FP, it comes out to be ~29lb/hr, and it feels a little better.

Do I need bigger injectors? With ~29lb/hr now, 30lbers would be worthless, what about 36lbers?

 

[vristang]

Well, I messed with the timing and fuel pressure more, I set the timing to 12* and 60psi on the FP. The back fire has become less common and the bog is ALMOST gone, but still there. I got it to pop once under a full load, and in passing gear it bucks and jerks still.

I pulled a plug and it is paper white with a small spot of tan (not much).

Since I upped the FP, it comes out to be ~29lb/hr, and it feels a little better.

Do I need bigger injectors? With ~29lb/hr now, 30lbers would be worthless, what about 36lbers?

60psi will cause metering issues, as the injectors aren't designed to with stand that much pressure...

This seems to indicate that you have a parts mismatch.
What color is the sample tube in the C&L meter? compare this to the C&L 'calibration' page...
What are the numbers on the MAS? s/b 'F1ZF' for the A9P.


If that isn't it, then I'm not sure what to look at next...

Did you run both KOEO and KOER diagnostic tests?

jason

 

[montegoman351]

I adjusted the timing, FP, TPS.
I got: 13*, 50psi w/o vacuum, and .95.
It still has a slight bog, but the whole way home it didn't pop once.
I'm still leaning towards a slight lean condition, but I'll give it a few days before I do anything else.

As for the KOEO, I get all the stuff I don't have- EGR,EVR,CANP,AIR, and such.
And as for the KOER, if I can hold the connector just right it will go partially through. I can hold the connector and wiggle it untill it goes through, then with a free hand, rev it, and it will go through then loose connection. So I need to clean both connectors and give it another shot.

Oh, and the C&L blue tube for 24lbers, F1ZF cleaned with MAF cleaner. And the 60 PSI was just for a tst drive, it's not permanent and I've backed it down.