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Aaron Pedroza
03-12-2003, 10:18 PM
I am having probs with my beast. Cold this thing runs like a bat out of h--l. Should approach my 12 second timeslip. But when it heats up, not water temp but under hood, it bucks like a wild stallion once it gets above 2500 rpm. I know, I know, electrical but I just replaced the wires recently with Taylor wires, the high heat ones, the coil only has about 10,000 miles on it, plugs are fresh, DIS has about 10,000 miles on it, the cam and cranck sensor were replaced when I built my motor about 8,000 miles ago. What do you think? I guess it could be a fuel prob but it doesn't really feel like it and why would heat cause that? Now I that I think about it I am kind of feeling like it feels like vapor lock, but how would heat cause that? Anything you could tell me would be great. Haven't been on much lately but I am going to finally get this running like it should and try to give John and Jim a run for their money here in Cali.

rivlee
03-12-2003, 11:42 PM
I've been MIA for a couple of years, just been back a few months, and this is the 1st time I've seen you. I see from your post you've made some progress. 12's! :p

As far as your problem: Vapor lock is obviously fuel that gets hot enough and with low enough pressure to partially vaporize which will interrupt flow. Have you checked your fuel pressure? A dirty fuel filter will sometimes give this kind of symptom.

Another idea is the dialectric paste under the DIS. If there's not enough, the DIS will overheat.

Just a couple of thoughts beyond the usual check the sensors. lol

Lee

Aaron Pedroza
03-13-2003, 12:00 AM
I will check that out. I am thinking that air charge gets so hot that it is causing problems. I have the smallest pulley on my S-Model blower so it is really overdriven. I am going to take it down a notch and see how that works. Think it may be the prob?

1BADSC
03-13-2003, 12:16 AM
I think the extra spinning of the blower is creating too much heat once the engine warms up. Sounds like maybe you are getting some detonation. Could try some higher octane fuel and see if it is more stable. It has been said by a few on the boards that turning very high RPM's with the blower is actually working backwards because of the heat it makes. I would try higher octane and a larger pulley on the SC. And by high octane I don't mean cheap octane boosters that don't work. I mean like real 113 octane or so on. between 18 and 20lbs of boost should require 108 octane on most cars. Just something else to think about. Could also try a spark plug gap at .32 instead of .54. Someone recently posted the part number for the smaller gapped plug.

Aaron Pedroza
03-13-2003, 02:06 AM
I have a lot of head work done and a lot of mods so the boost stays down to about 15 lbs. I also have an alcohol injection system to prevent detonation but that isn't helping. I doubt if it is detonation because I ran this motor for a good 10,000 miles before I started having this problem.

1BADSC
03-13-2003, 02:16 AM
It could still be a problem with detonation due to the high air temp coming out of the sc at higher speeds. If the cylinder gets too hot then the fuel will ignite before the spark goes.

David Neibert
03-13-2003, 10:45 AM
Hi Aaron,

I know you said your wires are new, but you didn't mention if it was bucking before the new wires went on.

I'm thinking it's ignition and not fuel. Every time I've starved my engine for fuel it bogged not bucked. Same thing with overheating the intake charge from overdriving the blower too much, it boggs it doesn't buck.

The only time I've ever seen one buck was DIS or plugs and wires.
I'm betting one of your wires is bad or not on the plug all the way.

David

Drnaline
03-13-2003, 12:30 PM
Had this very same problemo. I know you said you have fresh plugs, but you didn't say what brand? Heat range? Electrode material? All have very much to do with the way you Flyer runs. The best one's are from ford, not even autozone Motorcraft replacements are good enough. Get them from Ford. I'd be willin to lay some money on this one. I went through three sets of plugs, various brands. And a few Fords too. Before I figured it out. I think what your feeling is the flame getting blown out at a certain cylinder pressure. When it's cold the temp, not the pressure allows it to stay burning. I'm at seven thousand feet too, so i think my problem was compounded.

Aaron Pedroza
03-13-2003, 12:38 PM
Well I have autolite plugs, stock heat range(wanted colder but didn't have them), brand new Taylor high heat wires that I have been told WILL do the job. So what you're saying is it's the plugs. I have used these plugs for years and on all my motors including this one without any probs. I do think we are all coming to the same conclusion though. OD pulley to much and should get colder plugs. I just don't know why it would start after driving it for about 12,000 miles.

Aaron Pedroza
03-13-2003, 12:43 PM
You know I just thought of something, It did start happening worse when I had to put a cat on my car. When I first put cat on I got some pinging so I richened it up a little and with my alky setup I didn't hear it anymore. I guess that would be the beginning of it all. Thanks for all the advice, if you have any more ideas post them I would appreciate it but I think if I get a step colder plug and go to next step up on the pulley I should be ok. I guess I know what I am doing this weekend.

BlackbirdSC
03-13-2003, 04:05 PM
Hey bud, how's my motor's evil twin doin'? Been awhile and I think we've both blown 'the twins' apart. :)

Here's something else to think about.

Mine started bucking shortly after installing a good blower and MAC CAI. I couldn't figure it out. It was kinda random, but always at WOT and 3000rpm or up. Usually around 4000rpm. I checked the plugs, checked for vacuum leaks and didn't see anything. So I checked for codes and even though the CEL never came on it had a code for 'MAF out of sync with TPS' or some BS like that.

I put a volt meter on the MAF and noticed it would buck when the meter was reading 4.6ish volts or higher. I'd seen it hit 4.85V. That was on my cheap slow meter and over 10ft of wire (I had the meter in the car) that dropped the voltage another .1V. So, the meter was really seeing upwards of 5V. I had a 76mm C&L with a 36# tube.

I've since changed to a 50# tube and it SEEMS to be ok. Although I just picked it up from the exhaust shop having the cats replaced. The cats finally broke up the day I put the new sampling tube in.

I think the farther you push the blower porting and overdrive ratio the better the chance of this happening. I'm using an extensively reworked late model blower "Just like Chris Wise's" and a 18% OD.

Good luck,
Steve

Aaron Pedroza
03-13-2003, 04:34 PM
Ya, long time no hear. Been working a lot and trying to develop a clientele again. Things are starting to get going. This was driving me nuts for the last few weeks and I just finally realized that it did start shortly after I got my cats put on. I replaced my wires shortly after that too and put new plugs in because I needed it to pass smog. It ran good for a while with fresh plugs but then fell off. Hopefully the smaller pulley will do the trick for around town and I'll just change over to the 18% for the track with race fuel and a higher concentration of alky to keep the charge cool. I just noticed your times too, I have to get mine running right so I can pass you, I'm not that far away and I have never run this thing with the MAF and injectors in sync. You even have gears and I have stock gears with my auto. Watch out I'll be coming after you.

BlackbirdSC
03-13-2003, 06:42 PM
Ahhhh... welll... that time's almost a year and a half old now. :)

Since the 13.5 run, I swithced from 3.08 to 3.31 gears, added a bigger cam, switched from stock 94 blower to a ported one, went from stock pulley to 18% od, changed to dual 2 1/2" exhaust, added a 75mm TB and MAC CAI. Oh... and I have a pair of Hoosier Quick Time Pro's instead of street tires.

Soooo... once I tune the damn thing I'm gunnin' for a 12 too. This is gonna be a fun year. :D

Bill McNeil
03-13-2003, 07:19 PM
Steve,

Which blower do you have now?

supercatxr7
03-13-2003, 08:43 PM
Aaron,

What alcohol injection system are you using and where is your injection point? I have a kit from SMC (for Grand Nationals) that I'm planning on using. How tunable is your alcohol system?

mark

Aaron Pedroza
03-13-2003, 09:36 PM
I knew that would come up soon. I spent a lot of time an money making this thing. I made my own with a bunch of stuff but basically I am using a chemical pump adjustable from 60lbs to 100lbs or pressure. I also have a injector nozzle in the intake plenum right before the intake manifold that has several different sizes. I have the tank in the trunk and plumb it all the way under the car to the engine compartment which is triggered by a pressure switch and has a light in the car to let me know when it is on. It really works good too. I will be running with it off and have serious pinging going on and flick the switch and you hear nothing. It has allowed me to run pump gas and the smallest pulley on an S-model up until I recently made my exhaust legal again. It really works.

Andy 94SC
03-14-2003, 12:49 AM
Aaron, glad to see you back around!

I know a modified SC is a COMPLETELY different situation from a stock one but, I had this same problem when MY SC was stock.

Ran great cold, bucked like crazy under boost when warmed up, I had a plugged cat. I chased the problem forever before the cat finally split and began leaking. I put on a MN12Performance exhaust (My first mod, sigh) and the bucking was gone. I noticed some talk of new cats, and thought you might want to consider that. I think my plugged cat was tripping the knock sensor, causing the bucking.

Jim Demmitt Jr
03-14-2003, 01:10 AM
Glad to see you back!
Could this be like old times? ;) we ben flerting with the 11's real close now just a few more runs.hope you get her dialed in and running strong do some Match racing again

John is running strong now we are all going to be at Bakersfield for the March Meet hope to see you there take care "Hot Rod"

Aaron Pedroza
03-14-2003, 02:53 PM
Andy, I just put a new cat in, I only have one. It is a Catco 3" that may have 3,000 miles on it. I may be running a little rich but I am sure the cat isn't clogged. The cat just being there may be the problem for me. Jim, I am glad I finally have a little time and some money to get my car running smooth again. I don't think I will get my bird to 11's anytime soon but I may be able to give you a run for your money in brackets. I was in mid 500's consistently the last few times I ran, just have to make sure car is running consistently.

BlackbirdSC
03-14-2003, 05:06 PM
Bill,

The current blower is an ESM Dominion III that was custom made for me to closely match the work done to Chris Wise's unit. It's a late style core that has extensive inlet and inlet plenum reworking, retains the coated rotors with VERY close tolerances (.002"-.003" by coating the inside of the case), Ti shafts and billet reinforment straps welded to the sides of the case. Mine's even special enough to have my name stamped in the plates. :p ;)

Unfortunately, I haven't really had the chance to run the car WOT much since the new blower came in. I didn't get it until right before Xmas and it started snowing. Then, I added the MAC CAI and started with the CEL and bucking from spiking the MAF. Get the new MAF tube and the exhaust starts breaking up. Soooo.. Ijust picked it up yesterday from having the cats replaced and a Dynomax Ultraflow muffler (dual in-out 2 1/2") replace the Flowmaster as my resonator. It sounds a little on the ratty side now since the Ultraflow is a common chamber but has basically straight through pipes. I'll haveta weld an H-pipe in right before it and that should take care of some of the ratty sound. But DAMN does it rev fast now!!!! :D

See ya,
~S