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Bad News for my Cobra

spdpilot

spdpilot

Well-Known Member
Dante is a great guy, I went there yesterday with my car and was having him install the Snow Meth Kit and tune the car with all the new parts I put on.

We both thought it should be very straight forward.

The meth kit ended up being a pain in the rear for him to install and took 3 hours. He wanted to get it right, which I appreciate. He also had to completely reprogram a new SCT chip from scratch.

Needless to say, the car didn't hit the dyno until about 5pm.

He made several pulls with the car, first trying to get a baseline and then getting the meth kit dialed in. Changing jets, voltage setting etc.

He thought he had it all worked through and a pretty good tune, so he started to doing the final pulls and out of no where, the car went lean. REALLY lean. Then the next pull it was ok. Then the next pull it went lean again.

We both tried to figure out why this was happening. It could be a fuel pump, the new throttle body being off, or a vacuum leak.

He is building a new motor for his truck for this weekends race. He knew how badly I wanted to run this car this weekend. But without a new motor for his truck, he won't be racing this weekend either. He used his time up on my car and we stayed there until after 9pm last night.

In the end, we couldn't get it tuned until we find out whats wrong. I am going to work on it tonight and then hopefully take it back to him tomorrow morning and let him work on it as well.

Its not looking good. But the car put down 410 rwhp (by Dantes Dynojet conversion) at 5500rpm. Taking it up to 7000rpm I figure would have gained another 20-30. With a the final tune adding even more. All in all, I think we would have been in the 450rwhp+ range. Thats nearly 100+rwhp gain with the new parts and methonal.

Sorry for the long post, I just had to say something about what Dante did to try to help me.
 
Foxman

Foxman

Well-Known Member
running it should not even be a option!! if it is going really lean the normal agian something is wrong!!
 
Lordgufi

Lordgufi

Well-Known Member
were you running a data log on it when you did your pulls...

maf voltage/count (bad reading pulls fuel)
timing(good to log)
knock sensor(pulls timing)
injector duty cycles
fuel pressure

=)
tuning is a love hate kinda thing
 
S

sdsubzero4

Spring Valley, CA
Well, you were gonna run it til this motor blow anyways, so, why not. 410 is not a number to sneeze at either.
 
spdpilot

spdpilot

Well-Known Member
You got to undestand Dante. He has a reputation he wants to uphold and he doesn't do things half way. I just don't think it is in him to put what ever tune on it and let me go racing.

One pull it would A/F was running perfect. Then we would say...fine...everything looks good, lets make a hard pull this time, then about half way through the hard pull, it would go lean....I mean REALLY lean. So we would shut it down.

In fact, it was running so lean that for him to compensate, he would have to add 27% more fuel. It was a roller coaster ride. Then suddenly the A/F would be fine on the next pull.

My fuel system is stout. I have the BAP, 42# inj, 90mm maf, new fuel filter, fuel pump seems to right.

Not to get too technical, but I am going to hard wire the BAP (Boost a Pump) in tonight so it stays on all the time, instead of just off the boost reading.

Vacuum lines could be the issue. So I am going to check those tonight as well.

It has a high idle. like 1200rpm. So we think it could be the new Accufab Throttle Body. I am going to put the old one back on.

In short, if I find the problem, fine. Otherwise, I am sitting on the fence.

I mean, on one hand, I am pulling the motor after this weekend anyways, so I don't care if it goes. But on the other hand, if I race it this lean, it is like I am intentionally trying to blow it up.

Really bummed about it.

So many things, so little time.
 
spdpilot

spdpilot

Well-Known Member
Lordgufi said:
were you running a data log on it when you did your pulls...

maf voltage/count (bad reading pulls fuel)
timing(good to log)
knock sensor(pulls timing)
injector duty cycles
fuel pressure

=)
tuning is a love hate kinda thing
Click to expand...


He said he needed to run special software to read the MAF and test it on the dyno, which would mean starting all over with the tune on the chip.

Timing was "medium" and we intended to add some when we got the fuel A/F straight. We never got there.

Fuel pressure I am not certain he was measuring. Not sure how he would. I have a guage at home, so I might check that out.

I was thinking about the knock sensor....but that would pull timing and add fuel if it was seeing knock. Could be bad.

Injector cycles were fine and MAF was not pegged we don't think.

I was going to check also the Idle Air Control sensor. Clean it out. I have a spare one laying around also. I also have a spare TPS, so I am going to replace that tonight.

We will see....all I can do is try. I am considered nearly an expert on these cars and Dante is one of the best tuners in the country, so you would think between the two of us, we could figure it out. But there are never simple answers when something comes and goes.
 
Lordgufi

Lordgufi

Well-Known Member
intermittent problems are normally due to dying electronics or a corroded wire/bad ground.

Maf count would have Really helped you guys to see if it was a maf error or not.

This is an old school trick i learned with my old talon to check for boost leaks but it works for vaccume leaks as well.

take a end pipe coupling of pvc drill a hole and install a tire valve stem, then take any coupling and install that onto wherever the most stable place for it would be at the furthest point away from the engine is best because you test more of the system ( if your car is super charged using like a paxton type centrifical or something then the outlet from the SC to intake would be a good place, or even the inlet of the SC ) and pressurize the system to 4-5 psi, if you hear no leaks at that psi then its not a vaccume issue you would hear hisses . if you want to be Really sure then bump the psi to around 10 but past that and your wasting time unless your SC is hitting higher than that ( then goto that psi )

lets see what else.

Fuel pressure can be logged via the ecu i thought? i saw an option for it on my GT on my sct tuner.

always log the knock sensor. if they always read something then magically stop you will go lean when the ecu " thinks its safer ".

something you could try on the maf is to use a multi meter and read the voltage from the maf that way.

I know between him and you he knows what he's talking about and i'm sure your there also. i'm new to these cars but i certainly didn't know about special software to read the maf. i'm old school with my talon lol i tuned by voltages.
 
spdpilot

spdpilot

Well-Known Member
Lordgufi said:
intermittent problems are normally due to dying electronics or a corroded wire/bad ground.

Maf count would have Really helped you guys to see if it was a maf error or not.

This is an old school trick i learned with my old talon to check for boost leaks but it works for vaccume leaks as well.

take a end pipe coupling of pvc drill a hole and install a tire valve stem, then take any coupling and install that onto wherever the most stable place for it would be at the furthest point away from the engine is best because you test more of the system ( if your car is super charged using like a paxton type centrifical or something then the outlet from the SC to intake would be a good place, or even the inlet of the SC ) and pressurize the system to 4-5 psi, if you hear no leaks at that psi then its not a vaccume issue you would hear hisses . if you want to be Really sure then bump the psi to around 10 but past that and your wasting time unless your SC is hitting higher than that ( then goto that psi )

lets see what else.

Fuel pressure can be logged via the ecu i thought? i saw an option for it on my GT on my sct tuner.

always log the knock sensor. if they always read something then magically stop you will go lean when the ecu " thinks its safer ".

something you could try on the maf is to use a multi meter and read the voltage from the maf that way.

I know between him and you he knows what he's talking about and i'm sure your there also. i'm new to these cars but i certainly didn't know about special software to read the maf. i'm old school with my talon lol i tuned by voltages.
Click to expand...

Thanks!! Some useful info there.

To be honest, it was his shop and I would have dug around that data if he let me, but just me asking questions was slowing him down.

I would have assume with his tuning experience, if the dyno software logged it, he would be making sure everything was working that was logged.

He is the tuning expert, I know enough about the data, but he does it every day and I have to trust him that when I ask, for example, "is the ECU kicking the in the alternate fuel tables when IMRC's open at 3200rpm?" and he says, yes they are working, he knows what that means and is making sure it is happening. Same with MAF readings.

But if anyone has any suggestions, I am open to hearing them. I am far from knowing it all. But I must admit, having problems like these makes me a better mechanic when its finally fixed.

Oh but you should have heard this baby scream at full throttle!!! Never sounded like that before! Thought it was going to launch right off the dyno! I want to go racing!!!:evil:
 
yosemiddysam

yosemiddysam

Well-Known Member
Donator
Could your boost a pump be pulsating? I think they are band aids and just went straight to better pumps and PDFM.
 
Lordgufi

Lordgufi

Well-Known Member
indeed you should put a multi meter and ensure its getting a full 12+ v i know i refer alot to my talon but the stock wiring on that car forced me to use a relay with another 8ish gage wire directly from the battery.
 
E

ears

Well-Known Member
rough city dude,,,, i really dont know what to do other than what yall have already said!!! i know another way to check for vacuume leaks is somethin that cwo taught me!! take some tb cleaner and spray it around your intake points,,,, ya know your mani and all!!! and if your motor picks up speed then theres a leak!!
 
S

smashedheadcat

Well-Known Member
I know stuff happens sometimes but if he's as good of a tuner as you think he is, then he should be logging this kind of stuff. How is he correctly tuning your car without logging MAF counts/volts, load, throttle position etc.? It used to be done that way all the time but times have changed. If you log the STFTs they will show commanded air to fuel (lambda) when you transition from closed to open loop. A quick mash of the gas before making a full pull will show if the car is going to transition into open loop or not before making a full pull. This will pretty much eliminate the throttle position sensor. When making a full pull you need to log fuel pressure (or monitor it somehow), load, spark, maf counts, battery voltage (this may be your problem, it's worth checking into anyway) and air to fuel at a minimum. These basics can really help save time and engines.

Of course, I know nothing about your car at all so I don't know what all parameters you have to work with in the software and how the ecu strategy works off the top of my head. I do tune my 2003 cobra myself so i do have plenty of experience messing with it's tune. My last car was a built 97 cobra, but didn't do any of the tuning on it.
 
Lordgufi

Lordgufi

Well-Known Member
indeed back with my talon i logged. timing, injector duty cycle, knock, rpm, maf counts/voltage, o2 voltage. all of that was my Minimum log. but also with the software i was forced to use if i had more than that the software would skip paramaters waiting on the ecu to get me the whole stream.

these ecu's are much more advanced and much faster. you should easily be able to log all of those params on the fly with no issue. i know it can be done using even the sct logging software thats free on their website.
 
spdpilot

spdpilot

Well-Known Member
Well.... I dropped my car off this morning and I await the outcome.

I worked on it last night until late. Checked all the hoses, sprayed starter fluid to see I could find any leaks...none.

Changed out the TPS, IAC, and checked clamps on intake. Hard wired BAP so it's on all the time. Still ran at high idle.

I did check the PCV and while idling I clamped off the hose with plyers and noticed something odd. The hissing sound we heard went away and the idle dropped. But PCV wouldn't cause these problems I don't think. So Dante is going to replace it anyways.

We will see what happens.

thanks for all you help everyone!

I want to start tuning my car myself. Going to buy the software and proper guages etc to data log. I work on computers all day and I know cars, so I should be able to do this.
 
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