Help! HUGE disappointment at dyno 324 Hp and 372 FT LBS. torque

Today I resprocketed my bike and installed my flush mount signals..So I had only a little time to check a few things on the mustang..Vacuum leaks, plug wires, distributor, etc.

enyawix] I missed that it ran great for first 400 miles of ownership. I would check for vacuum leaks said:

Just going back to basics here - when I built up my 5.0 and ran it for awhile it started bucking, pausing before accelerating etc... I had two burned plug wires that would fire at idle but would arc to the headers under load. Equal length headers are hard on wires. Just make sure you don't have the same problem I did.

I don't know what kind of mufflers the car has but I had fiberglass filled mufflers back in high school that failed and pluged the exit of the muffler... car would run but not very well. If you're running rich you could melt enough fiberglass to allow it to enter the outlet...

Since you've already ruled out a compression issue, it's either fuel or ignition related. The fact that your plugs are black right away tells me you have a fuel issue - way too much of it. Get the wideband O2 sensors working and start tuning... You'll score the cylinders if you run rich for too long so be careful.

Click to expand...

I sprayed the wires down with water and found no arching...The look relatively new and have no corrossion on either end..
I've seen plenty of plugged cats and exhausts.... The car doesn't bog down like a plugged exhuast system under load...I have 3" equal lenght headers with a hooker x-pipe and single chamber 3" mufflers...Very loud and unrestrictive..the mufflers are tiny..I'm actually debatting switching to flowmasters dual chamber, just to quiet it up a little...

SQUEEZE&STROKE said:

Sounds like way too much fuel...also, the plug gaps are questionable. I had a very similar issue in my Lightning...turns out the plugs were gapped to large. I think both are contributing to your problem.

Try NGK TR7's...IIRC.

I put those in the L and with the correct gap, they worked awesome.

Click to expand...

TR7's are the part #?? How do I know they are the correct heat range, etc for my motor??? I'd be very interested in a chart or information to help me pick the correct plug and gap for my application.

1BADLXCOUPE said:

Yo Fella's. Lets look at the basics here. A NON MODDED, Factory 302 H.O. Engine could easily hit 324 RWHP with a D-1 Procharger, let alone a decked and tricked out 351 Windsor. Your Tuning is Extremely Off, If it is a reputable shop they would know this and would atleast help you solve your problem. I feel the problem lies with the Injectors and the ECU, maybe even the Spark Plug gap like someone noted earlier. I'm no engine builder but I really feel, the best thing to do right now, would be checking your code's and do a standard rundown from there.

Click to expand...

I'm starting to wonder if this is where I should start digging deeper before throwing a bunch of IGN parts on it.

2002BLGT said:

First thing I would do is pull the distributor itself and put in a stock replacment one that will work with with the 351 swap ........those MSD distributors are well known for causing untraceable problems

Click to expand...

The contacts all look good... What makes you think it might be a distributor problem seeing as how the problem happens under any RPM/Load condition while WOT...If it's not WOT it doesn't happen....I'm just curious if this is really worth messing with?

2000xp8 said:

It's about 200rwhp off, something is seriously wrong.
I'd suspect it's the standalone system. Which in most situations it's better for the professionals to handle.

If all you are expecting to run is in the vicinity of 500rwhp, at least drop down to 60's.
The sale of the 80's would fund the purchase of smaller injectors.

Click to expand...

+200 would be nice...Personally, if I could hit 450 with this set-up I'd be very happy.. I 'd be satisified with anything over 420....The dyno is brand new and just calibrated, so it doesn't read as high as some of the other dyno shops....Some other shops probably would have shown +30-40 horse on my set-up..The difference I don't know..But I know they are different..
Why would dropping down to 60 lb injectors be any different than dropping the pulse width on the 80's?? Do they have a finer mist?? Once I get the right adaptor's I'll be able to tap into the ecm.

bt15 said:

I would be looking at ignition for a few reasons. Ignition module problems could account for not only the running issues, but the starting ones, as well. In fact, I had very similar problems (though on NA engines) in both my 351 Bronco (turned out to be coil), and my 85 Twister II (ignition module X 2). Symptoms were similar to yours both during start and WOT. So, if you have a spare module and / or coil lying around, you may want to try ruling them out before you dump a ton of cash into other theories. I'll warn you that it's very difficult to bench test modern CDI boxes unless you have some pretty decent knowledge of the systems. Accel took back my box for testing twice and gave me the thumbs-up both times (which led me down a very expensive troubleshooting path). Finally, I threw on a stock Duraspark since nothing else was helping, and all my problems were cured. I sent the box back to Accel again, and they finally admitted that the box was bad.

Click to expand...

......

A test box would be very expensive for just a test part.....enyawix mentioned something about advance or autozone testing parts...If they can test the box for me, like I said above it's worth a shot....


I guess this is the approach I am going to take...If it sounds ass backwards let me know...

1.) I need to figure out what plug/gap I need....There has to be a method to do this? ...
2.) Once I get the right plugs and serial/usb connector I'll datalog my sensors and see if there is anything else the ecm changes with throttle position @ WOT....I'll check my timing to make sure it is where I need to be.
3.)If I don't figure anything out from step 1 and 2 try a new msd box and distributor...(these are expensive test parts, so I'll try this last.) Am I on the right track here? any other recommendations? If anything I should be able to see what's going on with my A/F ratio when I'm getting this problem.

Bullitt347, Thanks for the response.

I'm not sure what the timing is at. I'll deifently check it before going any further...
As for the exhaust side, I see where there could be a restrictive issue, but with the exhaust on this thing it's almost like a stright pipe...very unrestrictive...plus this problem hasn't always been their on this build... I was thinking of switching to 3" dual chamber flow masters, but if you think that's to restrictive, I'll stick with what I got..

On the dyno my A/F is @ about 10.8 to one coming out the exhuast pipe...Problem I'm having is exhaust leaks from the headers, where the headers slip into the 3" pipe and the flanges that bolt to the rest of the exhaust system....I don't really know what my A/F ratio is...I'm sure it's not 10.8:1...

Thanks everyone for all the help I've received.....You've given me a pretty good path to follow.... I'm going to wait for the serial/usb adaptor and buy some better gaskets for the headers/exhaust system and check/adjust the timing.....Hopefully by this time next week I'll have a good idea of my actual A/F ratio and have this problem cured....

Last question is how do I know I'm running the correct plugs?? My current plugs are NGK Racing v-powers... part # 7173...Yes they are copper..
Personally, I've never been a big fan of dual tip plugs......The "v-powers" have only one ground electrode..They are not like bosch platinum +4's....The "v-powers" look like a regulaur plug, except the center of the center electrode doesn't protude evenly with the rest of the electrode. It's shaped like a "V"...
I was thinking of maybe running a hotter plug, but I don't want to burn up the engine either..
Should I stick with the plugs that are in it now and just tune it with these plugs or get a hotter plug then tune it?? If I run a hotter plug I won't be able to lean it out as much...The less fuel in the chamber the better...let me know what you think.