306 H/C/I swap - now has problems idling

[DLo]

I've done a lot of searching and reading, and I'm just trying to tackle one thing at a time. I already printed out the surging idling check list, and will do that soon but I wanted to post up anyway to see if there's anything I'm missing.

Basically I have a 94 GT, and my friends and I tried a 306 swap on it. Here's the buildout: Bottom end - Fully machined production block (.030 over), Federal Mogul main bearings(#4125M), production crank, Keith Black Silvolite pistons(10.1 comp w/58cc), Hastings rings, Federal Mogul rod bearings(#8-2600CP) and Federal Mogul cam bearings(#1204M)

Edelbrock 60379 Performer Heads
FMS 1.6" roller rockers
Edelbrock 3722 Performer Cam
Edelbrock 3821 Intake
Edelbrock 3845 70mm throttle body
FMS 24 lb injectors
Granatelli 75mm MAF for 24 lb injectors
BBK cold air intake

First off, the car won't idle on it's own once it gets up to temperature. I pulled codes, and found 157 - so I know there's a problem with the MAF. The granatelli MAF came with a harness adapter, it has 4 wires on it, 2 of which got pulled out. I guess it's possible that I've got those flipped around when I tried to plug them back in. Other than that, we've tried hunting for vacuum leaks using starter fluid or propane to see if the idle would change. We've found nothing so far. Could the MAF be a cause of my car not idling? I haven't tried to drive it yet since you have to ride the clutch in order to keep it alive. A lot of people on another forum have told me over and over again to get a tune, but the local tuners all say the car should drive and idle. Would appreciate some input, my car's been down for 2 months and I miss it!

 

[Downshift]

Hey, Are you saying that on the harness that you might have switched two wires? Try clearing the code and sticking your stock one back on just for now and see if the code comes back. If it does it is most likely just the harness or wires and not the maf. Thats what I would do. Good luck.

Oh also part of the idle problem could be the cam with the stock computer..... Not sure on the specs of that cam but the computers can be really touchy.

 

[OnyxCobra]

yeah chances are the cam is giving your computer a lil trouble, also make sure your idle is set high enough, that was my main problem.

 

[Stangbangin]

I would suspect that maf. try the stocker. I doubt you ran a radical enough cam to necessitate a tune for it to idle. It will need one but should idle without it.

 

[DLo]

Yup, I'm thinking I might have messed up the two wires. Unfortunately for me, I think my stock MAF was having problems too. The car used to die every now and then at a stand still even after a tune up and I tried to clean up the MAF with alcohol and q-tips.

Here are my cam specs: Duration 282/282, Lift .498/.498. My problem isn't exactly a surging idle though right? It seems to lope now in a consistent pattern. What would you suggest for RPM range at idle?

 

[Trickflow.GT]

i had problems with my granateli maf..throw the stocker back in and test it again

 

[DLo]

Actually I remembered now, when I tried running the car with the stock maf, it ran worse. Wouldn't the stock maf just conflict with the bigger injectors?

 

[SMOKEDURVTEK]

Are they new maf's. Try cleaning the sensor with alcohol maybe... just an idea

 

[aaron427]

You can't put the stock maf back on because it is set up for the 19lb injectors, and you are running 24lb injectors. Start the car, and physically turn the maf and see if changes the idle. See if you can get it turned to where it will idle properly. You can also start the car and unplug your maf and see if it changes the way the car runs. I would start with that along with checking your fp,timing, and adjusting your idle as needed. Which I think someone mentioned before. That should at least get you started. You should be able to get the thing to run on the stock computer. At least to drive the thing some. Good luck

 

[Trickflow.GT]

Actually I remembered now, when I tried running the car with the stock maf, it ran worse. Wouldn't the stock maf just conflict with the bigger injectors?

If you want to run the stock elecronics on the maf you have to get a setup like C&L where you just replace the housing and sampling tube....this will account for the bigger injectors

Or you can get new electronics and housing like with the granatelli...

Surprisingly enough i have had better luck with the C&L having tried both mafs...the Granatelli MAF wouldnt allow the car to idle, pull hard, and it backfired and sputter. Replaced it with a C&l/stock electronics and voila idles great and feels amazing.

Im not advocating for C&L its just my experience...

Nick

 

[fastgtfairlane]

if it idles ok when first started, when it warms up, try turning the screw on the throttle body by the iac and see if that helps.

 

[DLo]

If you want to run the stock elecronics on the maf you have to get a setup like C&L where you just replace the housing and sampling tube....this will account for the bigger injectors

Or you can get new electronics and housing like with the granatelli...

Surprisingly enough i have had better luck with the C&L having tried both mafs...the Granatelli MAF wouldnt allow the car to idle, pull hard, and it backfired and sputter. Replaced it with a C&l/stock electronics and voila idles great and feels amazing.

Im not advocating for C&L its just my experience...

Nick

That's really close to what I'm experiencing! I can almost drive the car, it's just if I don't ride the clutch when I'm about to come to a stand still, it'll just die. I'm not sure why my car's throwing a code 157, but I think I'm going to return this Granatelli unit and try something else - either the Pro M, or maybe the C&L. Where did you pick yours up from? The old MAF just made my car run like crap, I remember trying it when we first dropped the engine in. Also, I can't turn the MAF, it's in place? I've read up on the entire air flow thing before on some other sites, but was kind of lost when I started reading that.

I'm not so sure my car backfires, but it does kind of sputter or sound like a misfire through the RPM band. It'll barely idle and I've messed with the screws as well. Seems to idle fine when it just starts up. I forgot to pick up a fuel pressure regulator and check my fuel pressure, so I'll have to look at that too.

One other thing, we tried to check the vacuum. 10 inches of mercury..... I'm almost at the point of regasketing my entire top end, just can't find anything!

 

[Trickflow.GT]

If you want to run the stock elecronics on the maf you have to get a setup like C&L where you just replace the housing and sampling tube....this will account for the bigger injectors

Or you can get new electronics and housing like with the granatelli...

Surprisingly enough i have had better luck with the C&L having tried both mafs...the Granatelli MAF wouldnt allow the car to idle, pull hard, and it backfired and sputter. Replaced it with a C&l/stock electronics and voila idles great and feels amazing.

Im not advocating for C&L its just my experience...

Nick

That's really close to what I'm experiencing! I can almost drive the car, it's just if I don't ride the clutch when I'm about to come to a stand still, it'll just die. I'm not sure why my car's throwing a code 157, but I think I'm going to return this Granatelli unit and try something else - either the Pro M, or maybe the C&L. Where did you pick yours up from? The old MAF just made my car run like crap, I remember trying it when we first dropped the engine in. Also, I can't turn the MAF, it's in place? I've read up on the entire air flow thing before on some other sites, but was kind of lost when I started reading that.

I'm not so sure my car backfires, but it does kind of sputter or sound like a misfire through the RPM band. It'll barely idle and I've messed with the screws as well. Seems to idle fine when it just starts up. I forgot to pick up a fuel pressure regulator and check my fuel pressure, so I'll have to look at that too.

One other thing, we tried to check the vacuum. 10 inches of mercury..... I'm almost at the point of regasketing my entire top end, just can't find anything!

I run a 94-95 C&L elbow, Fox Maf housing (the one with no bolts) with sampling tube for #24's, stock Mass air electronics, and a large K&N filter that is located in the engine bay....the bend before the maf on 94-95 CAI kits does not help the idling situation...

ill post pictures when i get batteries for my camera ahahha

Nick

 

[Trickflow.GT]

Found batteries....lol this is what i meant

I like this look a lot better then the cheap bbk speacial...

but to each their own...oh and dont judge my dirty ass engine bay lmao...my car has been sitting outside for 4 months with no car cover...

 

[aaron427]

Hearing your symptons then I agree on it being the maf. They are not known for being the best in the world. I have had good experience with the pro-m, and c&l. Even if bolted into place you can turn the maf a little. Hard to explain. I ran the fox style also on most of mine. That engine bay isn't that dirty! I have seen a lot worse! ha ha

 

[DLo]

Okay, I'm going to return the granatelli for sure then, and pick up a Pro-M. http://www.latemodelrestoration.com/products/Mustang-75MM-Mass-Air-Meters-For-24Lb-Injectors <---- which one should I grab? Seems like I've seen a couple instances where people have ran fox body ones. Don't know the difference really?

 

[Trickflow.GT]

Okay, I'm going to return the granatelli for sure then, and pick up a Pro-M. http://www.latemodelrestoration.com/products/Mustang-75MM-Mass-Air-Meters-For-24Lb-Injectors <---- which one should I grab? Seems like I've seen a couple instances where people have ran fox body ones. Don't know the difference really?

The only difference between 94-95 maf and a fox maf is that the 94-95 maf has a flange on the side going to the air filter...

Nick

 

[DLo]

Well, I know this is an old thread. But finally saw the tracking and it says it's out for delivery. Thumbs down for 50resto lately.. seems like they always have stuff backordered. A little disappointed, but otherwise their service is acceptable. Summit has always gotten my stuff here right away.

Either way, I certainly hope this MAF makes my car drivable and solves a good chunk of the "problems" I've been having. Will post back :thumb: Thanks for all of your help so far.

 

[Mr. OAM]

I am not a fan of Granatelli.


After you get the new MAF let us know how it does.

If you still have a problem and it is not air/fuel related then it sounds like you may be lacking compression. The cam/crank sprockets could be off a tooth. Also, what is your initial timing set at?


Steve

 

[DLo]

Somewhat good news! I installed the PRO-M yesterday. No complaints, it went in easily unlike the granatelli which I kind of had to ghetto rig up. No need for adapters, nothing! The CEL went away...... then came back intermittently. I'll have to pull the codes again.

But, upon initial startup, the car fired up. I let it warm up, and then hopped in, and didn't have to ride the clutch like I used to. Cruised it all the way up to 40-45 and had no problems. A couple of times when I came to a stop, the engine would lope too low and nearly die so I just had to give it enough gas to keep it going. Otherwise, it would idle on its own for the most part.

Let's see.. I believe we set the initial timing at 10 degrees, base timing? Should I try resetting my idle? It's not as simple as just turning the idle screw on the throttle body right, I have to go through and reset the system?

Either way, what a beautiful feeling it was to finally drive the car. Thanks for all of your help!