Sr20det starts, runs fine 2-4 seconds, sputters, then dies.

[ShaakeAanBake]

aI am running a sr20det red top with Gt2871R, JWT pop upgrade ecu, and supporting mods.

I recently replaced my clutch, full brake set up, and brake lines. My car had been sitting for 1 year and did not have any sort of problem before this.

I drove it for 2 days before this problem started. But, when driving for these two days. I had an intermittent problem with the car bucking/stuttering under 1/2 to full throttle between 1 and 3.5 thoundsand RPM. The second day when the car totally crapped out, It started stuttering around 2,000 rpm and I floored it out of aggravation and let of coasting downhill till I had to turn onto another road. When I turned onto the road and went to accelerate, the rpm dropped to about 1,000 stuttered as I blipped the throttle and died on the spot.

Here is the problem.

When I start it up. The rpm's go straight to 2,000 and it runs smooth for 2-4 seconds. Then it falls down to about 500-1000. If I try to blip the throttle to keep it running, the rpm drops to almost nothing then jumps back up to almost idle for a second and then back to almost nothing if it doesn't stall out. The TPS is working.

I have a professional working on it right now and he is stumped after trying a few things.

Here is what we have done, and nothing has changed. I replaced the distributor today, no change. I tried a different MAF from the same year 5.0 mustang although mine is from a Cobra, start it up without any difference. The fuel pressure is at 42psi, and doesn't fall off at all. Just sways between 38 and 41 when it is sputtering and then dies.

Just put in new spark plugs.

I found an unplugged wire today that is spliced into the yellow/red wire on the harness going into the ecu. It has a single male tip on the end. I'm not sure what this wire is for since I bought the car of someone who had the car built and doesn't know a thing about it besides what it cost really.

I think it is the MAF. But my mechanic is saying that when you unplug the MAF, the ecu should substitute it's own values or go to full rich and the car should be able to idle without it plugged in ????

Some one please correct me if I have been misinformed, as this problem sure seems like it is the MAF.

Any insight would help greatly.

[DaPCWiz]

if unplugging the maf made no change, doesn't that indicate that something is wrong with the maf?

[abunai the drifter]

Originally Posted by DaPCWiz

if unplugging the maf made no change, doesn't that indicate that something is wrong with the maf?

I too would say that it is a maf problem try swaping maf and see if that works

[ShaakeAanBake]

That's what I thought.

I swapped a MAF on there from the same year Mustang 5.0, but it was not a cobra MAF. When I started the car, it acted exactly the same.

But my mechanic is saying that when you unplug the MAF, the ecu should substitute it's own values or go to full rich and the car should be able to idle. ????

Some one please correct me if I have been misinformed.

The problem at hand certainly seems like it could be the MAF.

[chituntang]

Did you unplug the MAF and see if the car idle? If not, try it.
That unplug is not needed to make your car drivable, so do not worry about it.
Unplug both TPS and MAF, then see if it is any different.
A Cobra MAF is different from a 5.0 Mustang. So they will not work the same.

[chrisa]

Check your IC pipes as well. If you blew a hose off it makes it feel like a MAF problem cuz all the boost is escaping.

[ShaakeAanBake]

Yeah. I knew the cobra maf was different. It was swapped to try and see if ANYTHING changed at all.

Yes. I unplugged the MAF and nothing changes. Same old jump to 2 thousand rpm and idle high for 2-4 second, then falls on it's face and stutters till till it chokes itself out.

I'm heading over to where the car is in a few. I'll try unplugging the MAF and TPS together as you stated.

My next move will be locating another Cobra MAF. Money Money Money, it never ends.

Thanks.

[ShaakeAanBake]

Originally Posted by chrisa

Check your IC pipes as well. If you blew a hose off it makes it feel like a MAF problem cuz all the boost is escaping.

Yeah. I made sure they were all set when this first happened. That's happened to me a few times.

Thanks for the input.

[ShaakeAanBake]

I have ruled out the JWT ecu since I have only put about 300 miles on it since replacing and inspecting the internals.

[warauto]

Did you gap you sparkplugs ? Clean your MAF ? How is your vacuum?
I was having a similar issue, Turned out to be my sparkplugs

[ShaakeAanBake]

Originally Posted by warauto

Did you gap you sparkplugs ? Clean your MAF ? How is your vacuum?
I was having a similar issue, Turned out to be my sparkplugs

Yep, all of the above have been checked.

[ShaakeAanBake]

I'm going to give JWT a call right now see what their take is on this.

[ShaakeAanBake]

After talking to JWT, we ran a few tests and it has come down to the ecu.

I have injector pulse for 3 seconds, and then it cuts right out, coughs, and dies.

In order for JWT to swap their board over to the new ecu, it must be the exact part number.

I was hoping that it wasn't the ecu, because I just had Jwt do the same thing about 300-400 miles ago. Someone working on the car, must have crossed the terminals again. Same damn thing happened last time, only the car would not start at all.

If anyone has an A18-B92-G00, I could really use it.

Just send a pm.

Thanks

[jspaeth]

My car does this when it is warming up sometimes. As it warms up, the problem goes away....stumbling down low and upon initial throttle tip in. Once you get it going tho, it's fine.

Once everything warms up, it goes away and is smooth as silk.

[Fricshon]

please let me know how this turns out, I just posted up something very similar and I have no idea what is going on

[ShaakeAanBake]

Originally Posted by jspaeth

My car does this when it is warming up sometimes. As it warms up, the problem goes away....stumbling down low and upon initial throttle tip in. Once you get it going tho, it's fine.

Once everything warms up, it goes away and is smooth as silk.

I'm pretty sure that it can't be the same thing if you car runs. Or idles smooth for more than 4 seconds. Whatever controls the injectors in the computer is shot. NO pulse after 3 seconds.

If you read the first post, it explains the early symptoms. The injectors were cutting out when the car was bucking the first two days back on the road.

FR ^: Once i find a replacement and get things rolling, I'll post up the details.

What exactly is goin on. Is like what I describe in the first post of this thread?

[jspaeth]

Yeah, you're probably right then, missed the bit about the injectors cutting out.

[IcecoastR]

Formerly SHaakeaanbake..

Still dealing with the same issue after buying new stock ecu and sending it out to JWT for a board swap.

After waiting 7 weeks and not the 2 weeks that I was qouted. It still did not run, or even start after the 1st time I had plugged it in.

I contact Jwt and get no where with them. I wanted to send it back to get it tested that week, but they insisted it was a problem with my car and not the ecu.

So after contacting them 3 times, they finally agreed to take it back and re-test for a fee if it tested out in working order. So. According to them it did. I get it back, still same result.

So, I think..? Why not try my ecu out of my stock 97 kouki just to see if anything happens. Really didn't think my modded sr would run on a stock ka ecu without programming.

1st turn of the key, and there it is. UP and Running without any fluctuation of idle, running smooth. Revs to 2600 smooth as can be.

I immediatly call JWT and have the car running on the phone to prove to them that it does run fine, and starts EVERY time without a hitch and will run for as long as I keep it on with the stock ka ecu from my kouki.

Now, this jaggov I had been dealing with goes into this bs technobabble shpeal and is still trying to tell me that my car is the problem. Mind you, the car would not even turn over anymore with the JWT chipped ecu, let alone start to idle and then die like it did before I sent it to them.

According to my mechanic, others I have spoken to, and my experience with this car and others. It all points to the ecu That Jwt had their hands in. It could be a short in their board that was overlooked or doesn't register in their testing?

Fuel pump turns on, red light in ecu is on, starter turns over, have fuel and spark but wont start. I started it up once last week for the first time since i first recieved it back from jwt. This was after i had it running for a few minutes directly before with the other stock ecu. But it died within 10 seconds and had the funky idle as I described in my first post from years ago.

Will idle smooth till the cut at 2600 with the stock 97 ka ecu. But will not run with the Jwt chipped ecu, and Jwt claims it tested ok, and they put in one of their cars to go one step further and it ran??

Not sure which way to go at this point.. More testing. Have the ecu tested by an trusted local programmer. Go standalone or try to find another tune for short money?? At the crossroads...