Little more help please. Injectors.

[RemoW2112]

Still struggling to get my new 95 stang through emissions. Here is what I know. I have X302 heads, 1.7 cobra rockers, a E303 cam, with a 93 Cobra upper. To the best of my knowledge it is a stock GT bottom end. It has a O/R pipe, no idea the brand to flow masters

The heads had the wrong plugs, Autolite 25 I switched them to 104s and I have put in new cap, rotor, and plug wires.

I took it to my mechanic to check the emission readings, I have dropped from 2078 hc to 1200. Better but nowhere near the 220 I need. My mechanice thought that I was over injectored. So I got the number off my injectors and discovered 0280-155-931 which is a 28 lb Chevy injector. (That is what I have dug up online.)

I have read a bunch of the injector threads and not quite clear on a couple points.

1. Does it matter what lbs injector have if you make sub 300 hp?
2. Doesn't the computer control how much gas the injector fires?
3. I have some mix of Cobra parts. I am assuming pre 94 since the intake is a 93. Do I need a Cobra ECU with the bigger injectors?
4. Do I need a special MAF for the bigger injectors?
5. Can the wrong injectors (gm ) and size (28 lbs) causing my idle problem and rich running?
6. Depending on what I find out, anyone have a set of stock injectors they might sell cheap?

Thx all,
Dan...

 

[BlackVert]

absolutely, the bigger injectors can cause it to run rich. does the car have an aftermarket tune?

what mass air meter does it have?

does your state do the rollers, or just hook it up to the sniffer and idle and part throttle (but not on the rollers)?

have you tried getting low on fuel and putting in rubbing alcohol to lean it out?

 

[toyman]

As stated, and as well, I would think that without the cats you will never get it down to the allowable limits.

 

[RemoW2112]

More details

How do I tell what MAF I have? It is easy enough to see. There is no custom tune. So would I be better off going back to the 19# injectors?

We run at 32 mph for 2 minutes then they test idle only for 95. I am going to bolt the cats back in and may go to the rubbing alcohol.

 

[HISSIN50]

If it's a Ford MAF, post the number on it. I.e. the stock MAF starts F2VF as I recall.

If aftermarket, post whatever you make decipher on it in terms of brand and numbers (and calibration codes. E.g., any number with a # sign near it).

Agreed with the exhaust plans.

Any codes? Check even if the CEL is not illuminated.

Good luck.

 

[RemoW2112]

MAF pics

This is what is on it. The tube it screws to appears to be original and I can find no part numbers on it.

Just got a scanner plan to check codes after exhaust install.

Thanks again for all the help.

 

[revhead347]

Sounds like you have a can of worms with a mis matched MAF, and an injector that is not normally used. If you just need to get it through emissions, then get an adjustable fuel pressure regulator. Dial back the fuel pressure, and put about 3 bottles of Heat in the tank. You're still going to have to work out that MAF and injector problem eventually though.

Kurt

 

[HISSIN50]

It sounds like the injectors are about 50% larger than the EEC thinks they are.

I would just go back to 19's for the emissions portion of things.

 

[bayellowstang]

What color are the injectors? Stock 19# are orange and the Cobra 24# are blue. I have a set of both I will sell for any reasonable offer.

Emissions testing sucks. I'm glad here in PA we have the 5000 mile clause.

 

[chaos254]

Seems to me your overlooking the main issue with your high emissions numbers. You need to have cat's on there. Run the stock catted pipe for emissions testing and use your offroad pipe the rest of the time. The mix matched injectors/maf is an issue but even if you fix them... I highly doubt you will pass without cats.

 

[skeptiq]

Here is a fuel injector size calculator to help decide what the proper size injector you need for a certain hp: Fuel Injector Calculator from WitchHunter Performance

Important thing to remember, is the MAF should be calibrated to the specific # injectors you have. If not, then the computer will not be able to map the right fuel curve. Also, the cat will be an issue. As already stated, it's virtually impossible to pass emissions testing without the cats. Thankfully, in Ohio, we have to testing, whew!

Idle issues are tricky, our cars are notorious for hanging / surging idle, and unfortunatly there are so many varibales it's almost impossible to say what your specific issue is. Things to consider when diagnosing idle issues, IAC gummed (can clean with TB cleaner), TPS voltage, etc... I would however say that until the MAF / injector issue is fixed, you might end up chasing your tail trying to diagnose an idle issue with the mis-match.

Here is a series of articles that I have found to be of great help with idle issues: Mustang Basic Maintenance and Technical Articles See the "solving idle problems section of articles.

In my opinion, you should figure out the MAF / injector issue before putting time / effort into other things. If you don't have an aftermarket chip, then your best bet is to get an injector set that matches your existing MAF.

Good luck and let us know how everything goes. There are alot of people on here with alot of knowledge, so post up!!!

Ben

 

[RemoW2112]

Update

I found a set of 19# injectors locally and as a + I scored a set of stock valve covers. So maybe I can change the oil without having to pull the throttle body. I also hope that it will let get get rid of the phenolic spacers. I am not clear on if I need the spacer because it is a 93 cobra intake setup or because of after market valve covers.

That cats are back on with new O2 sensors and I discovered that one of the bolts holding on the upper intake was stripped. I pulled it apart and helicoiled it. I am considering studding the longer bolts on the intake.

So can anyone look at the pic I posted earlier and tell me if it is the 19# maf version?

If i can score a 94-95 Cobra upper intake will it bolt onto a 93 Cobra lower intake?


Dan...

 

[HISSIN50]

If that sensor is in the stock MAF housing, it should be correct.

The same meter is used on all 94-95 Mustangs. The EEC is what takes care of the 'calibration.'

So if you have a GT EEC, it would correlate to 19's. If you had a Cobra EEC, it would correlate to 24's.

 

[WhiteCobra95]

MAF's measure air flow. Fuel Injectors inject fuel at a certain rate. If you're using different parts than stock, your ECU needs a chip to recalibrate for the changes. Modifying a MAF curve to offset the load signal for a certain injector flow rate is a hack fix. Load percentage is calculated from mass air flow and indexes numorous tables. With a "fuel injector" tweaked MAF thsi signal is shifted low and indexes maps in the wrong spot.

Regarding the emissions, I have seen some people lean out the mixture and retard timing to pass. However, the cats plus reinstalling the 19 pounders should do the trick.

 

[final5-0]

About those inj size programs you see all over the net

Note a couple of important things

1) They use motor hp NOT wheel hp
2) Fuel pressure can make a difference

1 Say you are talking NA aftermarket h/c/i stick trans combo

Such a combo is around 350-370 motor hp
You don't wanna think in terms of wheel hp to arrive at inj size
unless
You factor in drive train loss ... in this case 298-315 wheel hp

2 Ford uses a default value of less than most of those programs use
therefore
The inj size is gonna act smaller due to less pressure

See how you could undersize if not being careful here

Grady