New Intake, Possible Fuel Cut?

[SleepyGST]

Hey guys, I realize there are millions of threads about this, but I can honestly say i didn't find another thread the same as this, but I don't really have a whole lot of time right now to just search for too long, so any help is greatly appreciated!
So i purchased a new intake and got it installed, everythings tight, all the lines are in the correct spot. I went to take a run with it, and it sounded and felt great until I got on it a little bit and I hit a wall and when I got back my parents said that they heard a huge pop. I have not done a boost leak test cause I'm confused as to what the problem is in the first place. My mod list is up to date. Sorry for such a novice question, but any help is greatly appreciated!!

 

[casperfast]

i chased a similar problem like this down until i FINALLY found this coil pack. yours look anything like this?

 

[casperfast]

by the way, i went coil on plug immediate after i found this and have never had the problem again i have about 6 300m coils in good shape if you want to go this route, i also have a few spare stock coils laying around if your interested.

 

[SleepyGST]

Yes thats exactly what it looks like! I couldnt believe that it could be eaten up like that. Thanks so much for the reply! Alright if I pm you in the next few days for the oem coil?

 

[boost97gst]

Btw, they dont even have to look like that to cause problems. But if they do, that most def is where your troubles lie. You must drive ## dsm about as much as i drive mine , saw the first post was sometime back in '12. Hope you have luck(think you will).

 

[SleepyGST]

Lol Yeah its definitely been plauging me for a while, but I told my mechanic to check my coils and said they were fine. This is the first car where im trying to do things myself and be my own mechanic and everything so i have room to learn. This is my first build as well, I just wanted to figure out this problem before modding any more. Hopefully this cures it because ive already done quite a bit.maybe this all happened so I could look over all those things and make it this much healthier!

 

[WES_393]

Be aware that your average COP systems (without a CDI controller) have been proven less than/equally as powerful as the stock ignition. So don't rely on a COP to solve the issue.

Here's how to test the coil pack:

You must be logged in to view this image or video.

 

[boost97gst]

Remember: You can bench test a coil til the cows come home but the real test is under high heat and high duty cycles. Thats when they fail. Higher the rpm, higher the duty cycle basically. Your triggering the gates(PTU) thus applying primary voltage to the coils more often obviously, as the rpm raises. Thats when you can get failures.

Make sure your gap on plugs is good, i havent read everything so i assume you have, just thought id throw that in the pot too. low boost and you can run .028 for sure. When you get up in the 25-30+psi range gotta gap em smaller.

And i agree with wes(wiseman for a reason). Dont turn to COP unless its more of a cosmetic thing.

 

[SleepyGST]

Thanks wes, ive read that somewhere, so im going to stick with replacing it with oem. Id rather it run well than look/sound cool. And yes my plugs are .028 with ngk premium blue wires, new fuel filter, fuel pump, and no boost leaks. Hopefully soon it will be time to continue my build

 

[SleepyGST]

I changed my coil pack with a known good one and I took it for a test drive and it still bucks. Im 100% stumped. does anyone have anymore suggestions? No boost leaks, ngk blue wires, ngk bpr6es at .028, 190lph pump, peak 14lbs on t25 with 3" catback/test pipe, hard snorkel with k&n cone, 1g bov.

 

[We're on Boost]

Well, because you are in Sheboygan, which is where I've had the best smoked lake trout ever (long ago) this problem has got to go down.
So I just read back a ways, and, even though I didn't think so at first, I think I agree with your mechanic (in post 37) that it is hitting fuel cut. Yup, even with the stock down pipe, which seems weird, but I have no idea what a stock 2g down pipe looks like. And you are apparently catless with a test pipe, that would help you to hit fuel cut.

So your Wally 190 is a forward step, but running with the stock non-adjustable fuel regulator, you can't raise the fuel pressure. So that combined with stock injectors, you have a pretty severe limit on how much fuel can get in there. Your MAF sees enough air flow to make your stock ecu throw a fuel cut.

This is where you either fool the stock ecu by putting in one step bigger injectors and adding a piggyback controller (like the apexi one) to lean the thing back down, or else you get your ecu modified with a custom chip so you don't have to fool it, but you still would put in bigger injectors because you are going to need them anyway. With bigger injectors you could probably keep using the stock fuel pressure regulator up to a point.

The modified ecu - you would need to get it socketed if it isn't already, then the same guy would program a chip for it using your input info - fuel pressure, injector size, etc, and the fuel cut would be programmed out of it.

Your other running problems that you have noted could be totally separate issues that you might still have after doing these mods.

By the way, isn't the BPr6 plug 1 range hotter than stock? You'll want to get those out of there if you ever get this problem solved. Maybe they could be your "Winter in Sheboygan" plugs.

I don't remember if you ever said, what happens if you turn the boost down so it maxes at like 11 or 12 psi - is it ok then? Maybe you can't turn it down because you don't have a boost controller?

 

[SleepyGST]

Haha glad you liked it, but I guess the reason I didnt want to get a piggyback or link yet is because countless people have modded the exact same as me without any problems, so I thought something had to be wrong. I wouldnt want to continue modding or whatever without fixing this problem, but apparently ive just overran the mafs limit. One thing that scared me about an safc was splicing into stock wires, and link is too expensive so I was thinking getting a black box ecu and going that route. I dont have a boost controller so I didnt raise the psi at all that I can drop it. Its just so hard for me to believe that im hitting fuel cut especially knowing how many people have done the exact same as me with zero problems. Could it possibly be my maf failing by not being able to read aa high as it should?

 

[WES_393]

Your not overrunning the MAF, it's good for much more airflow than your pulling. I've personally ran a Small 16g at 25psi+ without issues from the 2g MAF.

But if the MAF was malfunctioning, that would be a different story and is totally possible.

 

[We're on Boost]

but apparently ive just overran the mafs limit. One thing that scared me about an safc was splicing into stock wires, and link is too expensive so I was thinking getting a black box ecu and going that route. I dont have a boost controller so I didnt raise the psi at all that I can drop it. Its just so hard for me to believe that im hitting fuel cut especially knowing how many people have done the exact same as me with zero problems. Could it possibly be my maf failing by not being able to read aa high as it should?

Well you are not overrunning the MAF, because the 2g MAF can do a lot more than where you are at right now. If it is fuel cut, it would be caused by the stock ecu getting sensor readings that are high enough to make it call a fuel cut. And I have no idea where the stock 1997 ecu calls for a cut. But if the MAF is failing, yes that could be the problem. Maybe the ecu is failing.

I remember thinking a while back that it would be cool if you could tap into the signal wire that takes the Hz signal from the MAF to the ecu with a meter that is capable of reading Hz. An example would be a Fluke 87. Your auto mechanic friend might have one. You could watch what the frequency goes to just before you hit this black hole thingie. You would have to find out from a 2g expert what frequency triggers fuel cut in a 2g. Then you'd have a better idea whether it is really fuel cut or not. Most people would do this measurement with a logger, but you could use a standard meter. You would put the other probe of the meter to ground. A good meter will have such a high input impedence that it won't suck enough current out of the MAF signal line to hurt anything - in other words the car would still run the same with the meter attached. You could find the signal wire by getting the correct plug diagram, similar to the ones Wes showed when you guys were talking about coil packs, or by finding out the color code and terminal position of the signal wire where it enters the stock ecu.

What is a black box? Do you mean a stand-alone ecu? Do you mean a fuel-cut defender?

Do they still put friggin salt on the roads around there in the winter?

 

[SleepyGST]

If my maf was bad it could cause a funny idle correct? My car idles like it cant find the sweet spot, its totally different from a vacuum leak idle. Couldnt remember if I mentioned that or not, sorry. And yes by black box i meant the 98-99 black box ecu. But this is why im confused, if I have no boost leaks and im not reaching the mafs limit, then there obviously has to be an issue and id like to figure out what it is before I add more variables or just use a tuning solution to get rid of fuel cut and ignore the problem.

But yeah Boost, I talked to a guy and he said "if you knew what we spread on the roads you wouldnt drive on them" . Its a real shame.

 

[ryztriumph]

I couldn't help but get sucked into this thread. I don't have a solution honestly, all the things I would have said to check, you've done. You might want to try a different maf and see if your problem persists.

Per ecmlink's site, a 2g unhacked maf is good for 50 lbs until fuel cut, at 2700hz. You would be lucky to be doing 25 lbs with that t25.
http://www.ecmtuning.com/wiki/maffrequencylimits

As for the maf, I have one I know is good. If you are interested you can pm me! Good luck with your car, and don't give up!

 

[We're on Boost]

I think that if the MAF was bad, it could cause erratic idle. Or some circuit in the ecu could be bad.
The thing that pops into my head about erratic idle is the "idle switch" which would be located right on the throttle body. It is positioned actually like a throttle idle stop screw like carburetors have, or had. The position of this thing has to be adjusted properly so that the switch inside of it is making electrical contact only when you are foot off of the gas pedal.

Also, it has to be actually working, and with age, and salt on the roads, this little switch is a target for corrosion which will mess up the electrical contact it is supposed to make.

Anyway what it does is it tells the ecu that the engine is supposed to be idling. If this switch doesn't work the ecu doesn't know you are idling. I'm not sure that the 2g has this switch, but I would think so. The 1g sure does. You can buy a brand new one (OEM) for not too much, or with a multimeter you can test the one you have - you would be looking for low contact resistance, and smooth mechanical action (not acting sticky). Don't just use the "continuity tester" in the meter. Try to get a resistance reading (ohms). It should be really low, like a few ohms or less (close to 0) when the switch is closed.

But this is why im confused, if I have no boost leaks and im not reaching the mafs limit, then there obviously has to be an issue and id like to figure out what it is before I add more variables or just use a tuning solution to get rid of fuel cut and ignore the problem.

But yeah Boost, I talked to a guy and he said "if you knew what we spread on the roads you wouldnt drive on them" . Its a real shame.

If you are not reaching the limit of the MAF, your ecu will still throw a fuel cut at a certain MAF Hz because the ecu is programmed to do that to protect the engine. The designers knew that past a certain MAF Hz your stock fuel pump and injectors reach their limit. Past this limit the engine will gladly keep pulling, making more hp, but the fuel/air is getting leaner and leaner. As it gets leaner you'll get knock. Do this a bunch of times and your nice new car won't even make it through the warranty period. You'll have a massive engine failure. Getting through the warranty period is a big deal with the designers.
The knock sensor helps to protect by retarding ignition timing, but knock sensors don't last forever - they fail, and a knock sensor isn't the complete solution anyway. So they design this fuel cut feature into the ecu to shut the engine off when some certain MAF Hz is reached, to protect against this ever happening. That's why you have to either get that changed by custom ecu programming, or work around it, to make more power.

That's why I think it would help if you actually knew what MAF Hz you are reaching just before your car hits this wall. I think it would tell you whether you are really hitting the normal factory fuel cut. If you aren't, then there is some other unsolved issue. If you are, then you can quit looking for weird stuff wrong with your car and concentrate on the upgrades necessary to go around or eliminate the wall.

BTW, if you go about using a digital display meter like a Fluke 87 to read MAF Hz as you are accelerating, the numbers will fly by so fast on the display that you won't be able to read them. Well wait, the digital display only updates 2 or 3 times per second anyway, so you'll never actually see the peak number reached. But here's what you do. Most of these meters have a "peak" or "min-max" hold feature that you can turn on. Then do your pull in the car. The meter will remember the highest (peak) frequency reading it got and show it to you afterwards.
The display is slow, but the meter internally is very fast. In the manual you can look up specs for "Frequency Counter Sensitivity" and "Min Max Recording" to get a clue. My meter was designed over 20 years ago but even so the specs claim good response to changes down to only 1 millisecond of duration, and good accuracy over a very wide frequency range.
Some meters might even be able to record the whole thing and play it back for you in stop-motion like a logger.

A cool thing about using a meter (like above) is that for measuring frequency, you could probably use an inductive pickup instead of a regular meter probe. In other words, you wouldn't have to cut open your MAF wire. You could just clamp the inductive pickup to the insulated wire, and there you go. You would have to have an inductive pickup made for that particular multi-meter. The other meter wire would have a regular aligator clip type end on it that you would clip to ground somewhere.

 

[SleepyGST]

Thanks for the quick replies guys, and thanks boost for that detailed answer, that really cleared a lot of things up for me! But you speak of this fluke 87 but I have never heard of this. It must just be a datalogger huh? So my question is, if im planning on going black box ecu with ecuflash/evoscan should I just get that right away to log instead of buying two loggers and go from there or what?

 

[We're on Boost]

Well the Fluke 87, and other meters like it, are multi-purpose meters (multimeters) that cost a little over $400, and the guys who would have one would be electronics technicians, electronics hobbyists, possibly an electrician, and possibly an auto mechanic. I thought maybe your family auto mechanic would have one, or similar.

They are not made specifically for cars, they are just made for anything in general that is electrical or electronic. If you ever want to measure DC volts, DC amps, AC volts, AC amps, resistance (Ohms), frequency of a signal, capacitance, you know - any of that electrical stuff, this is what you need. You can get cheaper ones for sure, but I don't think they will measure frequency. So I'm hoping you know a tech who would have one and know how to use it, to do what we're talking about. He could ride in the right seat using the meter while you are driving doing a few pulls. It's something every car guy should have ideally, but being expensive, it might not be at the top of your list of priorities to actually own one. Mostly you use them for trouble-shooting. Hmm, that's what we're doing isn't it.

Before I forget, I have a nice sketch of the connector side of a 2g ecu, with some of the wire positions labeled, including the MAF (MAS) wire which is #90 (you would need the sketch). I could post that here if you want it.

If you can go ecuflash/evoscan, I imagine that would be a great way to go. It seems to be a very common way to go with the 4g63 evos. I don't know anything about how to make it work with a 2g DSM, and I don't know anything about the 98,99 ecus. I don't know why they are different from the 95,96,97 ecus. But yeah I would go with that stuff and be happy ever after, probably, heh heh. You might still need a multimeter at some point for, yup, trouble-shooting. This is a DSM you know.

Hey if I can get imageshack to work I'll go ahead and post that sketch, because the comment written right above it is kind of relevant. Don't pay any attention to the wire colors given - those are ecuplus wires, not stock ecu wires. This is from my ecuplus manual which was written by Tom Collins. The comment is:
"On the 1995-1999 Talon and Eclipses, and the Evolution VIII, the stock ECU contains four connectors, numbered as shown in Illustration 4. This shows the stock ECU as you'll view it, facing the connectors in the end of the metal enclosure."

Wow, ImageShack sure screwed up a few months ago when they changed their website all around. What a mess. anyway here's the pic:

You must be logged in to view this image or video.

[/URL]Uploaded with ImageShack.com[/IMG]