Garbage gas mileage, 10mpg

[5spd GT]

30lb injectors would be almost PERFECT if "our" combos had a tune...look at it this way...

Stock 87-93 5.0L = 225hp with 19lb injectors
93 Cobra 5.0L = 265hp with 24lb injectors
Our combos = 340hp with 30lb injectors

The top two have "factory tunes"...

Without a tune 24's would probably be fine with "our" combos...but 30's are definatly ideal for ours with a tune...and by looking at my chart...it almost looks like with a "factory tune" you can squeeze in some 36lbers

 

[Grn92LX]

Little update: The only issue i'm having is a not so good cold start idle. When the cars first started for the day. Its a little better than how it was with the old maf. Other than that, it runs/idles fine. I guess I should say im lucky as some have horrific idle problems and non stop surging/stalling. The car seems to pull better now that I have my optimizer hooked up. Dunno if its in my head. Im hoping to dyno soon. For comparisons sake, I played with my boys 94GT 306 making 323hp/348tq, from a roll and we are basically dead even. I'd win by 1/2 a car or he'd win by 1/2 a car. That was before the tremec, 75mm tb, 30lb maf and tune up.

I just did new plugs, cap and rotor. I went to Ford to get a new coolant temp sensor but they didnt have one and they wanted $43 Double what mustangs unlimited wants. I was in a tune up kinda mood

For the record, I did have my car "tuned" by a local shop. What a f'n waste of money and I hope that shop burns down to the ground with massive death and destruction inside Im pissed, but I try to forget that.

Anyone wanna buy an accufab 65mm tb/egr?

 

[5spd GT]

Little update: The only issue i'm having is a not so good cold start idle. When the cars first started for the day. Its a little better than how it was with the old maf. Other than that, it runs/idles fine. I guess I should say im lucky as some have horrific idle problems and non stop surging/stalling. The car seems to pull better now that I have my optimizer hooked up. Dunno if its in my head. Im hoping to dyno soon. For comparisons sake, I played with my boys 94GT 306 making 323hp/348tq, from a roll and we are basically dead even. I'd win by 1/2 a car or he'd win by 1/2 a car. That was before the tremec, 75mm tb, 30lb maf and tune up.

I just did new plugs, cap and rotor. I went to Ford to get a new coolant temp sensor but they didnt have one and they wanted $43 Double what mustangs unlimited wants. I was in a tune up kinda mood

For the record, I did have my car "tuned" by a local shop. What a f'n waste of money and I hope that shop burns down to the ground with massive death and destruction inside Im pissed, but I try to forget that.

Anyone wanna buy an accufab 65mm tb/egr?

Yeah my car (after sitting overnight) doesn't want to idle...I have to stay on the gas for about 15-20 seconds to get it to idle and then it is fine...

I'm sure the messing around was at a local track right

Yeah that coolant sensor (I'm wanting to replace that soon also) is $30 bucks from 50resto...

So what did that shop say they did or what were they supposed to do? Glad you had a fun time over there and you got your money's worth

 

[Stang717]

Ok, after reading this thread.. Ive come to a conclusion.. Im sure a lot of you guys are gonna back me up on this.. First off, charts are of great importance.. Its not like some computer geek sits in a room, and bs's this stuff.. Its actually tested.. In a real car, with a real engine, and a real driver... Second.. Your 30lb injectors, which you swear by, are overkill and why you have sucky mileage.. It sounds to me that your car, off the bottle is makin somewhere in the 250+ range..(Just an educated guess) Now, my 89 vert with gt-40X heads, b303 cam, gt-40 upper and lower, 1.7 roller rockers, and a hell lot more, is makin just under 300 at the rear wheels, with torque at 305. The kicker is... I have a 255 fuel pump with 24 lb injectors, followed by a 75 mm mass air, and 70 mm TB.. Seems to be pretty sufficient, wouldnt you say?? I get approx. 15 mpg city, and 17+highway.. Now, to prove to you that you dont need 30lb injectors, here's some math for ya..
take your BHP, which in my case, is roughly 335 or so.. take the hp and multiply it by.5 (break specific fuel comsumption for N/A car) multiply the answer by 1.175 (85% duty on injectors) and divide the total by 8 (#of cylinders) Looks like this..(HP)x 0.5 x 1.175/8.. In my case.. 24.6.. THis is the injector size needed.. Now, dont forget that is only 85% duty.. Finally, no, i didnt just pull this formula outa my A$$.. goto http://www.accufabracing.com/technical_faq.htm#FPR if you dont believe me..
OK, thats enough for now..
Mike
P.S Sorry for the long message..

 

[5spd GT]

Ok, after reading this thread.. Ive come to a conclusion.. Im sure a lot of you guys are gonna back me up on this.. First off, charts are of great importance.. Its not like some computer geek sits in a room, and bs's this stuff.. Its actually tested.. In a real car, with a real engine, and a real driver... Second.. Your 30lb injectors, which you swear by, are overkill and why you have sucky mileage.. It sounds to me that your car, off the bottle is makin somewhere in the 250+ range..(Just an educated guess) Now, my 89 vert with gt-40X heads, b303 cam, gt-40 upper and lower, 1.7 roller rockers, and a hell lot more, is makin just under 300 at the rear wheels, with torque at 305. The kicker is... I have a 255 fuel pump with 24 lb injectors, followed by a 75 mm mass air, and 70 mm TB.. Seems to be pretty sufficient, wouldnt you say?? I get approx. 15 mpg city, and 17+highway.. Now, to prove to you that you dont need 30lb injectors, here's some math for ya..
take your BHP, which in my case, is roughly 335 or so.. take the hp and multiply it by.5 (break specific fuel comsumption for N/A car) multiply the answer by 1.175 (85% duty on injectors) and divide the total by 8 (#of cylinders) Looks like this..(HP)x 0.5 x 1.175/8.. In my case.. 24.6.. THis is the injector size needed.. Now, dont forget that is only 85% duty.. Finally, no, i didnt just pull this formula outa my A$$.. goto http://www.accufabracing.com/technical_faq.htm#FPR if you dont believe me..
OK, thats enough for now..
Mike
P.S Sorry for the long message..

He's making more than 250 horsepower ...try over 300rwhp...I think he has got 308rwhp? or something like that...

Your only making 305 torque...yikes...guys with me and Grn92lx's combo are making 330 torque at the wheels or in that area...

Here is the chart you should look at when considering how big of an injector is ideal...(from above post)...


Stock 87-93 5.0L = 225hp with 19lb injectors (from factory)
93 Cobra 5.0L = 265hp with 24lb injectors (from factory)
Our combos = 340hp with 30lb injectors

The top two have "factory tunes"...

Without a tune 24's would probably be fine with "our" combos...but 30's are definatly ideal for ours with a tune...and by looking at the chart...it almost looks like with a "factory tune" you can squeeze in some 36lbers...

You did good getting 24lb injectors for your car...our "combos" are a bit more aggresive than yours...therefore we need a more "aggresive" injector...

I believe the duty cycle needs to be down more from 85%...no need getting close to maxxing them out...

 

[Grn92LX]

Mike, not to be a d!ck, but I dont use internet charts to help me. I use common sense and wideband a/f meters on the dyno. FACT, 24's were NOT enough for my combo. FACT 24's were perfect with my trickflow combo, but car ran LEAN with the addition of my ed curtis custom grind camshaft. Im talking 16:1 a/f in some spots, 18:1 in some spots. FACT, with the eec working properly with the maf, I could run a 42lb injector in my car and get good mileage. My car made 295rwhp running LEAN, dunno where you came up with 250?? My yq was about 329ft/lbs. car started making 300 ft/lbs around 3k. With that I ran 109 mph trap speeds.

david, I had the shop do a chip tune on my car. It worked ok at first but it got worse so I went back to have them fix it and they couldnt. It kept surging/stalling uncontrolably. I ended up fixing it myself. When I called them and told them i fixed it myself, I was treated like $hit. I hope that mother ****er burns to the ****in ground

 

[Michael Yount]

Grn92 - I think you're missing the point. The fact that your car ran lean is not solely attributable to injector size. MAF calibration plays a huge role. The other data listed are correct - 24's have enough flow capacity to safely support your HP level. If you were running lean with them, the issue wasn't injector size; it was something else. No doubt you solved it by putting larger injectors in, but something else was amiss (probably maf related) if you couldn't get the mixture you wanted with 24's at your power level.

 

[Grn92LX]

Michael, I tried 2 maf's a c&l 76mm and a pro m 80mm. Both ran lean, but with 55psi of fuel pressure it ran 'safe' but still not good. hard to explain. My buddy has a similar set up and ed curtis recommended 30's for him. And like I stated above, before swapping in the ed curtis camshaft, the a/f was perfect with the 24's. The lean problem happened with the new cam. A sure sign of needing the bigger injector IMO. For over 2 years the a/f was dead on with the 24's and c&l until the addition of the new camshaft.

To be honest with you Michael, I regret doing the ed c cam. Lots of problem$ arrised from it and lots of headaches. Live and learn I guess.

Mike

 

[5spd GT]

To be honest with you Michael, I regret doing the ed c cam. Lots of problem$ arrised from it and lots of headaches. Live and learn I guess.Mike

You got to pay to play...

Well the cam changes many things on a vehicle...should have been expected

 

[Grn92LX]

I should have kept the TFS 1 cam, added longtubes, 75mm TB and kept the nitrous. Either way you look at it, it would have been an 11 second car on drag radials if my local track were still open.

Heres a recap on my headache: Installed ed c cam jan 03 I believe, blew head gasket on nitrous feb 9, 03, fixed car and added longtubes and milled heads .020". Removed nitrous and sold it. Went to the track a few times ran a few 12 sec passes @ 108-109 mph. Dyoed the car and made a dissappointing 292-295rwhp because the car was severely lean. THis is where the real headache began of trial and error adding parts to fix it. Then once I added the 30lb injectors I wasrewarded with severe idle problems BUT it felt noticeably quicker. Eventually I had a chip done for the car and well that didnt work out too well (I still hope that mother ****er shop burns down ) Its running really good now and I finally got a new trans that i've needed for well over a year now guess what? The fuggin track shut down for good!!

 

[Michael Yount]

Mike - I understand, but your post doesn't alter the situation. Unfortunately, even though people think you can do it, simply plugging in another maf to test the current one usually doesn't provide much useful information. I have no doubt that you've got it running better now; I'm merely suggesting that the solution is coming from the 30's in conjuction with the maf you're using. With a properly calibrated maf, the 24's have plenty of capacity for your HP level. If they weren't flowing it, it wasn't because they weren't capable of it - it was because the computer wasn't holding them open long enough - which is likely traceable to an maf not accurately telling the computer how much air is actually entering the engine.

My custom cam from Buddy (likely MUCH milder than yours) was probably the best money I spent on my whole engine. I couldn't be any happier. 'Course, easy for me to say as mine is knocking down 19 around town and 24-26 on the highway. That's with the 19#/hr injectors and a ProM 75mm maf.

 

[Michael Yount]

The folks who seem the happiest with drivability and efficiency on hotter combos have usually used a tweecer to input the actual transfer function (airmass to volts curve) from the calibration of the maf into the ecu. This assures an almost perfect 'reading' of airflow into the engine by the ecu.

 

[bgjohnson]

okay here is another idea, I took time to read the entire thread, and nobody has come back and said anything else about your o2 sensors(by the way if you replaced them alread disregard this) but if you spliced them together and the splice had a little higher resistance or is grounding out somwhere that is also may cause horrible gas mileage. I recal sombody earlier in the thread say" o2 sensors have nothing to do with how the car runs" well I say bull**** to that, have you ever worked on a car with a grounded out o2, it will even die because it's so rich, the computer has no idea what the o2 is saying since it's grounded out and just dumps the fuel in. that may be another thing to consider. and grn92LX, that is an awsome MPH on that quarter mile run

 

[Michael Yount]

bgjohnson said - "..." o2 sensors have nothing to do with how the car runs" well I say bull**** to that, have you ever worked on a car with a grounded out o2, it will even die because it's so rich, the computer has no idea what the o2 is saying since it's grounded out and just dumps the fuel in."

This is not entirely true. Everytime the car is started cold, it's in open loop without the O2 sensors functioning or contributing to the computer's decisions about mixture; the same thing is true at wide open throttle. The computer uses other means of calculating the fuel requirement under those conditions. When my car was originally converted, the fellow that did it 'lost' one of the plugs on the harness as it got hung up inside a tunnel behind the strut tower when he was pulling the harness through. The plug that was 'lost' was the one that input the O2 sensor's signals to the ecu. As a result, not knowing any better, he simply left the O2's unplugged from the main harness. My car ran completely without O2's plugged in for 6 years and 25K miles. And with no check engine light, we never knew anything was wrong. It got 16-17 mpg around town and 22-23 on the road, which seemed reasonable to us for a geared-up brick. So, while screwed up O2 sensors can cause problems, under many conditions, the engine can operate quite fine without them too. There's simply not a one-size fits all answer to what happens when the O2 sensor data either doesn't show up, or is bad/incorrect/corrupted.

 

[Grn92LX]

Michael, another example I forgot to mention- My friend has an afr 165/rpm/FTI combo. He had 24# injectors and needed 55psi of fuel pressure to get the a/f nice. With his car all tuned he did run 12.40 @ 110.xx on et streets. Then, we went to the track again and he was running mid 13's @ 101 with NO changes. Seems that the eec adapted his FP changes. He also noticed that cars on the street he used to beat he was now loosing to. He put in 30lb injectors as recommended by me and also ed curtis. I told him to put the FP to 39psi. He hasnt dynoed or been to the track since because like I said, the damn track shut down

Bgjohnson, my splices are good. I do, however, believe that cutting into the wire and splicing will in fact add resistance but I didnt stick an ohm meter on it. I might look into new o2's and see if I can find one longer in length. I know the parts store ones come in different lengths but not sure about oem ones? When I spliced them, I used 1 gauge thicker wire, crimped it, then out heat shrink on it, then convoluted tubing and electrical tape. I do telecom work for a living so wiring isnt really a problem. Thanks for your suggestions. My mph was decent considering the state of tune it was in. I would have liked to see 112+ but we'll never know. I wonder if my idle could clear up even better with new unspliced 02's and a new coolant temp sensor? My idle isnt good the first start of the day but after that its great.

Mike

 

[blkstangman88]

i get 24mpg on average with mine, im happy

 

[LarsD]

The folks who seem the happiest with drivability and efficiency on hotter combos have usually used a tweecer

I got one of these. Finally got my MAF curve dialed in right and my car has woken up big time. I never though having the correct MAF setup was so important until I got my most recent tune setup. Now my car pulls harder than it ever has. Plus I get 22mpg city/hwy on 89oct. IMO you need to ditch that "MAF optimizer" and get a real tune. Mine was just a little out of whack, and it was really holding my car back. Now I'm anxious to get back to the track!

 

[5spd GT]

i get 24mpg on average with mine, im happy

You got a stock motor

 

[blkstangman88]

ya i know i got a stock engine, thats y i bought a protege so i can drive it and rip the engine out of my stang and rebuild it with twin turbos!!

 

[5spd GT]

ya i know i got a stock engine, thats y i bought a protege so i can drive it and rip the engine out of my stang and rebuild it with twin turbos!!

I know I got 23mpg one time with 373's, all the bolt-ons, and full exhaust...so I was impressed but I averaged around 18mpg...I don't know what my mileage is now after adding the h/c/i? I'm working on a tank right now to get an estimate...