Cobra lost power after installing Crane 2031 cam

I hope everything turns out well.

I am having to rebuild my stock cobra engine due to the previous owner neglecting to do anything about the vibration from the engine due to a bad balancer. I am going to install a 2031 cam and do some minor home porting on the stock gt40 heads while I have it apart. Mainly smoothing the short side radius and smoothing the valve guides and port matching. I have a tweecer r/t and some free dyno time so I'm gonna do my own dyno tune after I get it all together.

Yeah I think the power will be all in the tune myself. If they won't reburn the chip you'll probably end up having to take it somewhere else to get it done unfortunatly. I hope it all turns out well.

There is nothing worse then paying for work to be done only to find out the place doing the work didn't do all the things they were expected to do. This is the reason I do most of my own work.

SVTtripleblack said:

Well, I talked to the tuner yesterday morning and asked him to do a dyno run w/out the chip. I could tell he was a little insulted that I was questioning him about the way he tuned it, but I don't really care. I told him that I would prefer that he tuned it though the ecu instead of doing it manually. He said he didn't think taking out the chip would make any difference, so hopefully he follows through with it. He hasn't gotten back to me yet. I'll let y'all know how it goes.

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Been workin WAY too much lately

Sooooo ... haven't had any time to see what all has been goin on

but ... I have been curious if you are getting things all sorted out and it looks
like you are makin some headway

Hey ... you paid for a service and you didn't get what you consider a fair
rate of exchange

I'd not feel all that bad for speaking up like you have done

He needs to know you expect things in a certain way and not just some
generic or run of the mill kinda tune

Just basic or general info about my Week End 95 GT Toy tune

I run about 36 total spark and its all in by 2500
I run the mix at about 12.75 to 1.00
I got the tip in retard nulled out

A note about the above info would be ...........
I run just a tad more squeeze with
the small AFR chambers
a cut on their decks
and hg's that are a bit on the thin side

It all boils down to the fact that ..........
I gotta pump in the 93 stuff which is kinda costly these days

If you go less aggressive on the spark ...........
you might be able to run a lesser grade of go fast juice

Hope you find a bit more power in the new tune

Grady

you definitely should have gained power, I don't have dyno numbers cuz I'm running untuned (just advanced the timing and adjusted the TB) and I saw a nice gain at the flashlight drags (1/8 mile racing on an air strip, set up just like street racing, only it is legal and sanctioned, no timeslips though). I used to lose badly to my buddy with a built 01 GT with a built auto and stall and now I am dead even with him and even nosed out a half fender win end of last season against him. I'd say maybe your shop didn't properly degree the cam. This really doesn't make any sense, to be honest I'd go with the suggestion above to check and see if the swap was even actually done. Does the car have a choppy idle? If not, I would say there's a good chance you've got yourself a stock cam still.

just saw your new post.

Was the car running fine until it warmed up? Mine did that when we first got the swap done, Idled and ran like a champ while pulling it around to the front of the shop, but once it warmed up and went into closed loop (stopped dumping fuel) the car bucked and died. The only thing I had to do was manually adjust timing to 16 degrees and I played with the air bleed screw on the throttle body (essentially creating a really small vacuum leak) until it idled consistently. I have had it stall on me on occasion at a red light here and there (maybe once in every 50 lights), but thats no big deal to me, I will be getting a full tune after I finish my H/C/I, LT's, maf, TB, injector, and gear build.

SVTtripleblack said:

I am positive the swap was made. I got back my old cam, springs, and pushrods. The car did have an awesome lumpy idle, but now it won't start at all. The car felt like it picked up some midrange, but it was raining last night so I couldn't get on it too hard. If the cam was degreed improperly I think I would have noticed either poor low end power or poor top end power. This doesn't seem to be the case.

Right now I have the battery unplugged and I'm waiting to try it again tomorrow, but I don't know what else to do.

I think I will see a lot more power with a good tune if I can get this thing started.

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Hopefully that will work out for you, it sucks to see this not working out for you. If it's not the degreeing or the tune, I honestly will be baffled... Obviously, a cam with stock heads will never yield major power gains, I didn't expect them nor did you, but you certainly should make more than a couple extra hp, and you damn sure shouldn't lose any power. The only thing a cam should make noticeably different is the RPM range of the power, and also a power increase. I did notice the mid range power of mine fattened up considerably, which you said you also noticed.

Dunno man, keep us posted.

I would have to say from what you're describing, it sounds like the fuel might be the issue... I don't know how to reset the fuel pressure though, hopefully someone will chime in with some knowledge.

I know you checked things around the area of the pcm but it sure sounds like
there may be a bad connection since things have been disturbed a good bit
all around that area lately.

I'd look at the service port since he pulled the old chip out to see if anything
looks out of line.

You kinda need to keep WOT conditions separated from cruising around town.

If you are at a light to medium load .....
a mix greater than 14.7 is not uncommon.

At WOT ....... a mix of low 12's would most likely be a bit fat

As for the dizzy being at 14

You really can't tell a whole lot by that kinda thing

You don't have a clue about what is going on with your spark unless you know
how he is making his adjustments

See ... here is the deal with spark on SBF's since their inception

Well ... first ... lets just cover the basics

You got total amount of spark
Then you got how it is controlled

Now ... back to SBF's

They've always produced max WOT power at 36 give or take a few
and
You'll always pick up power if you get it all in quicker

Now ... having said those two things ... lets talk about our pcm 94-95 Stangs

The amount and rate of advance is controlled by the spark tables in the pcm

If you don't have pcm access ... you can't obtain both of those objectives

Allow me to post up an unmodified spark table from a 94-95 Cobra



First ... A bit of basic info for those who've never seen such a table

On the left side you see load with bottom idle and top WOT
Across the top you see the rpm
All values are as they are with the fact the dizzy is set at OEM value of 10

What you basically would do is ..........

Increase the value in the top row (WOT) to around 36
and
Have it come in quicker by being all in by 2500 or there abouts

Now ... look at what happens if you don't have pcm access

To obtain your best WOT performance you want 36
sooooo
You have to twist the dizzy an additional 10 to obtain the 36 total

That just won't be a possibility as the mid load values will be too high because
when you do the ... dizzy twist dance ... its a global kinda thing and its in effect
at all loads.

That much of an increase will wreak havoc with your mid load values
and
Most likely produce the dreaded ... ping thing

Of course ... it goes without saying .............

Twisting the dizzy will do nothing about the rate of advance as well

Summing up

In your case ... if he was only doing mechanical tuning

You would add 4 to ALL values as he bumped the dizzy setting up by 4

Basic Stuff Really

Maybe some will find it helpful

Grady

A quick pcm reset procedure for you

Disco the neg batt cable

Turn on the headlights for 15 seconds

Turn off the headlights

Reinstall the neg batt cable

PCM Reset ... Done

Grady

SVTtripleblack said:

I tried to start it again last night after I had the battery unplugged for several hours. On my second try of cranking the motor for several seconds it fired up for about 5 seconds and then died again. I even removed my computer and checked all the connections and everything looked ok.

When I look at the big picture, only two things were done to this car that may keep it from cranking over.

1. The fuel pressure was bumped up with the stock regulator (Against my wishes).
I would have rather had the car running lean untill I was able to get it tuned by a REAL tuner. Does anyone know how to set the pressure back to stock?
If I'm looking at it right, it is a little dial behind and to the left of the distributor. I think it is located between the distributor and the upper intake manifold. There is even a hose coming out of it that says high pressure fuel.

2. Would the ignition timing set higher keep the car from starting? Do I need to reset it to a base of 10? I wouldn' t think I would, but I'm stumped.

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if you have the stock regulator how did he adjust the pressure? at this point if everything was installed properly you should check the fuel pressure and verify you have spark. the part by the intake and distributor is the schrader valve. get a gauge and hook it up there.

also having the timing advanced should have no effect on starting.