Couple Problems..... Soft Code???

[BowTie Eater 5 Liter]

well ever since i put my motor together the fawker hasnt ran 100%.

what ive done is edlebrock aluminums, 1.7rr's, e-303, cobra intake, underdrives, full exhaust, sn-95 alt, 70mm t-body, 73mm c&l, afpr, 190lph pump(stock 19lbers unfortunately).

my problem is after 5000rpm the car doesnt like to work, it backfires and gets really stoopid... i just changed o2's, fuel filter, fuel pump relay(was getting a code for that). i get a "soft code" if i tromp on it through the first 3 gears(or more). the check light will come on and stay on until i let off, and i can not pull a code up for it. i was thinking the o2's were the problem, but now im leaning towards mass air sensor??? i havnt found a way yet to actually test to see if the meter itsself is screwed? does this sound like a condition of a bunk mass air meter?

another q, what should i have the fuel pressure set to running my combo(as ive just got the stock injectors for now) or should i leave it at 39psi?

thanks

[Lethal5Oh]

I could be wrong on this one but sounds to me like your running to small of an injector. Your soft code is probably a lean code, since your under full throttle the computer is unable to add the extra fuel that your engine now needs do to the upgrades. ID recommend going with atleast a 24lb injectors and matching MAF sensor. You could try upping the fuel pressure to say about 45. UP it in small amounts and see if your check engine light stops coming on.If you havent upgraded your fuel pump, u might look into that. Fuel pumps are inexpensive insurance. Definetly help with TOP END fuel starvation problems. Good luck

[Jeff Chambers]

I'd concur. My first suspicion would be a lean condition. You really need to get the car to a good dyno shop and see what's happening under load.

[BowTie Eater 5 Liter]

its definately not a lean issue, 190lph pump, i know the injectors are at there limit, but they should hold. it was having this code when i just had stock stuff on the engine also, someone mentioned the dizzy could be off a tooth, but i set base timing to 13* spout out. i dont know why or how being a tooth off would affect the car this much, because timing is still set to 13*???

[rwhite65]

I would doubt it is off a tooth, especially if it runs decent up thru the 5,000 mark. Every time I have ever been off a tooth, if I got it to run, it was not runnin worth a hoot.
Ryan

[Joel5.0]

Originally Posted by BowTie Eater 5 Liter

my problem is after 5000rpm the car doesnt like to work, it backfires and gets really stoopid... i just changed o2's, fuel filter, fuel pump relay(was getting a code for that). i get a "soft code" if i tromp on it through the first 3 gears(or more). the check light will come on and stay on until i let off, and i can not pull a code up for it. i was thinking the o2's were the problem, but now im leaning towards mass air sensor??? i havnt found a way yet to actually test to see if the meter itsself is screwed? does this sound like a condition of a bunk mass air meter?

another q, what should i have the fuel pressure set to running my combo(as ive just got the stock injectors for now) or should i leave it at 39psi?

thanks

That's the problem....anytime the CEL turns on, there should be a code registered in memory, not having a code means there's a problem with the EEC-IV...what kind of problem?.....anything from a bad EEC relay, wiring, VPWR supply, ground, fubar'ed PIP signal, bad TPS, bad alternator (bad rectifier causing electrical noise) or,.......fubar'ed ECM.

How did the voltage check on the MAF go? , did you get rid of code 56? LUK

[vristang]

As stated directly above, it could be a ground issue. The EEC is pretty sensitive to ground/power issues. It may be worth the time to double check the grounds in the engine bay.

I don't think you can get the 5.0 dist "a tooth off." You can easily get 180 out (which I have done more times than I care to admit). If you put the dist. in off center by a few degrees, you simply rotate it until it is where it should be. It is possible to have the dist hit the manifold or something and still be out of range, but other than that the dist is fine unless you get a full 180 out.

jason

[Unit 5302]

The two problems may be unrelated. I would tend to agree with the comments about the engine being lean as a likely source for your top end backfiring. With the kind of horsepower I'd expect that combination to be capable of achieving with a decent tune, you'd need about 60psi on the stock injectors to simulate the stock injection cycle. You're running 39, which would be spot on for 24lb/hr units.

As Jeff stated, getting it to a dyno might not be a bad idea, considering you could easily blow the engine if you're as lean as we suspect you may be.

[rwhite65]

Jeff and Unit offer reliable advise. I would stay on the safe side and look into the lean issue.

I know very little about fuel injection, but it makes sense with the better heads, the stock injectors might have trouble keeping up.
Ryan

[Jeff Chambers]

Try to find a dyno shop that has a datalogging system for the EEC-IV. We use SnEEC to datalog the earlier systems and it'll record key parameters like MAF voltage, injector duty cycle, O2 voltages, ECT, ACT and others. Its a wonderful help when tuning the EEC-IV cars.

[vristang]

I just Re-read your original post and have to agree with lethal50h. Those small injectors are probably all that needs to be changed, maybe the pump too. The combo you listed should not require dyno tuning, although it would help in confirming what the problem is.

Bump the fuel pressure, and see what happens. If things get better, then start saving for the new injectors and pump.

Your combo is pretty close to a stock 93 Cobra, so I would think that the 24lb injectors would be justified.

jason

[vristang]

I ran a calculator I have...

To get the same flow from the 19lbs as what you would get from the 24s, you would need to bump the fuel pressure to 46psi. This high of a fuel pressure with stock injectors may cause control issues (as in the pressure prevents the injector from closing), I can't say for sure though.
Try bumping up to 43psi, and see what happens. If things get better, then you know it is a fuel problem.

Please come back and let us know how it goes.

jason

[BowTie Eater 5 Liter]

ok, going to bump fuel pressure to the 43-35 area and see what that does. hopefully it helps.

ive got a line on a set of 30lb fms injectors, i know that they are more than i need as of now, but would they work better than the stockers? i plan on a bit of juice soon or some sort of power adder, in which case i dont think the 24lbers would be sufficent? should i grab these 30lbers or just get some 24's???

ill post back tomorrow and see if there is any changes

unit5302, nice to see your still offering your advice after all these years, cheers!

[Joel5.0]

The blinking CEL/no codes condition is trying to tell you something about the system's behavior/performance.........listen to it. My 2¢. GL

[BowTie Eater 5 Liter]

ok, well listening to my motor underhood, the distributor sounds like its arcing out, its not constant, but there is a click you can here and its most definately coming from the dizzy. what in the dist. could cause this? it used to be a barely noticeable noise but its constantly getting louder?

[Joel5.0]

If it sounds like spark is arcing, check the condition of the cap/rotor...if it sounds like a "chirping" sound, check the condition of the vanes rotor and any signs of it rubbing against the stator sensor....this last possibility could be causing your CEL/no codes and backfiring issue. Hope this helps.

[BowTie Eater 5 Liter]

its definately not a chirp, its like "click click click" first thing i checked when i noticed it was the wires to make sure they wernt burnt through, then had a buddy listen to the motor as i lifted it off idle and it is definately coming from the dizzy....

i just reset idle and reset computer, going to drive it tomorrow and then pull codes and see what it comes up with