Changed injector size.....not idling correctly

walter89

Registered User
i just got my new engine put in the other day and i threw in some #36's and it originaly had #30's. Now it does not idle smooth at all. Does the MAFS need to be recalibrated for the correct injector size to fix this problem. If so what kind is the best to get. thanx
 
you could get a pro m maf but i would go back to the 30 s unless you have lots of mods , i have lots of mods and mine still runs rich with 30 s in it , i had it leaned out running good with eec tuner till the tuner quit on me i want another eec tuner it felt like 20 more horse
 
call C&L performance and buy a 73mm MAF meter and tellt hem you have a supercoupe and ask what color sampling tube you need, dont drive or remove the injectors for now, you can also have a custom chip made to use those injectors without changing the MAF meter
 
You need...

You CANNOT change the injectors without re-calibrating the computer/or changing the MAF sensor. The stock injectors are 30 lbs and the ones in there now are 36. Therefore, you're dumping WAY TOO MUCH fuel into the cylinders. Imagine a garden hose that's 1/2" in diameter and another is 1" diameter. You now have the 1" when you had the 1/2" before. A LOT MORE FLOW THROUGH 1"!!!!


Get a C+L air meter with the 36 lb sampling tube (quickest fix and easy to do), or get a chip to re-program the PCM to accept the 36 lb'ers.

Otherwise, change back to 30's. A stock motor or close to stock will run great on the stock injectors. I have them on my 91 and run completely free-flow exhaust and MAC cold air intake and no problem and FAST AS HELL!!!


Don
 
Get a stock '94 or '95 MAF

I modded my 90 XR7 with a '94 blower and went to 36# injectors plus other mods. What a kick in the *** that was. I just used the stock 94 MAF off my 94 SC and it ran great and strong. The 94 MAF is calibrated for 36# injectors since they were the stock injectors for the 94/95 SC. I now have a C&L 73 on my XR7 and really did not see any power gain over the stock 94 MAF.

Ed springer

90 Black XR7 5-speed: 70mm TB, Fresh Air Intake, '94 Supercharger, 5% SC Pulley, Raised SC Top, I/C Fan, UD Pulleys, 190 l/h Fuel Pump, 36 lbs Injectors, Headers, Magnaflow Muffler (no cats) with stock resonators, 3:27 Gears, Ripper Shifter, 73mm CL MAF (Blue Tube), Magnacore Wires, NGK Iridium Plugs, Royal Purple Lubricants and Rear Spring Air Bags.

94 Red SC Auto Piece of CRAP: 70mm TB, Fresh Air Intake, Stock 90 SC Pulley, Raised SC Top, I/C Fan, 190 l/h Fuel Pump, Headers, Raven Muffler (no cats) with stock resonators, 3:73 Gears, 76mm CL MAF (Gold Tube), Magnacore Wires, NGK Iridium Plugs, Royal Purple Lubricants, TRANSGO Shift Kit, Pro-Torque 2500 Stall TC, Haydon Auxiliary Transmission Cooler, Tokico Struts & Shocks, American Racing 17” Sniper Wheels, Michelin Pilot Sport A/S Tires and 235 RWHP with 315 LB-FT Torque.
 
edspringer said:
I modded my 90 XR7 with a '94 blower and went to 36# injectors plus other mods. What a kick in the *** that was. I just used the stock 94 MAF off my 94 SC and it ran great and strong. The 94 MAF is calibrated for 36# injectors since they were the stock injectors for the 94/95 SC.

Guys, Don is correct. No Ford mass air meter is calibrated. Use of a stock mass air meter from any year or model will most likely result in too much fuel or not enought fuel in some circumstances. If it seems to be working for you then you have other issues which is making it seem ok but believe me it is not.

Pro M isn't even in business any more, but you may be able to find a used one calibrated for 36's. C&L makes a meter which will put your AF back into correct range for you.
 
sorry i forgot to mention this earlier, but the engine is not stock. it was rebuilt by a racing shop and has a bigger cam and rods in it and has had some major head work done to it and is fully balanced. So you're saying that i just need a new maf and sampling tube/or reprogram the PCM to accept those injectors?
 
Regardless..

Regardless of mods, you need the properly calibrated MAF to allow the proper fuel. I would suggest again, the cheap way out is the C+L meter. I'm not sure if the 94-95 housing will work properly with the ealy model electronics. I would not want to point you in a wrong direction.

Again, no chip you can "buy" will make the fuel correct. Only a properly tuned chip which is usually dyno-tuned, will make it perfect.

People forget that these cars are NOT the easiest to modify properly, although when done so, are AWESOME!!!!! Just can't bolt on certain items and expect perfect results.


Don
 
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