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Discussion Starter · #1 ·
Okay, took the car out onto the highway for some high boost tests to make sure its running alright.

At not quite WOT... or occasionally AT wot... when the tach got to about 3400 rpm's (everytime it happened it happened at 3400) the car would sometimes feel like it lost all power for a split second. Its NOT a subtle feeling AT ALL. It feels like the car jerks. When it goes above 3400 rpm's without problems, it doesnt have problems. A friend and I took turn letting her breath ;) ... She pulls like an absolute monster until the occassional JOLT... It sounds like its accompanied by a bang... but that could be seriously amplified since my entire exhaust is off... no cats/mufflers... just straight ATR downpipe lol...

Anyway, we're going to have a look at the ECU tomorrow.

The spark plugs were replaced 500 miles ago. They're gapped at .032. The wires were also replaced at that time.

When it happens, you dont lose boost, the guages stay about the same, until of course you let off... cause generally the sound scares the SHIT out of you. My heart stopped everytime it happened. If its knock... its fuckin hella knock dude... I dont think thats knock, cause it was happening at about 14.3 psi... but a couple times we got it up to about 15.2 psi... (its COLD tonight)... without problems...

So basically, a hard kick back... loss of power for a split second... Until tonight I had thought it was my y pipe partially blowing off because it had a relatively weak connection to the plenum. But its on there, that shits not moving REGARDLESS. So its not that. The fact that it feels almost like a fuel cut off, and it only happens at 3400 rpms (doesnt matter which gear your in) makes me think its electronic.

Any one feel any different? I'll be working on her again tomorrow with an eclipse owner. ANY input is appreciated.

Thanks, Adam.
 

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The Reality Of Tomorrow
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What you are experiencing is referred to as "miss" - an ignition misfire. These are caused by a number of things, but most often by an improper spark plug gap, resitance in your spark plug wires, or a weak coil.

With the cold weather you may need to gap down your plugs some more, or maybe swap out coils with someone else to see if you have a weak coil.

-m
 

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Discussion Starter · #3 ·
/bump

Would a bad coil lead to blow out (every once in a while) at 3400 rpm's and ONLY at 3400??? I don't think so...
 

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I hate to say this but we may have the same problem. See if your fuel press is being adjusted properly with the regulater. I have been all over my car looking for the problem. Look up the post missing at 4k and you can read about it. I am back to running stock boost and still getting it. Some times it pulls hard with out missing and other times its missing like crazy. I am now looking at the regulator to see if it shot. If thats not it I will look at the injectors. My plugs all look the same black around the treaded part and light at the ground stap.(rich then lean) I hope this helps because I have been pulling out my hair for months!
 

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Discussion Starter · #5 ·
Have you checked the ECU?? I'm going to check that out today, it sounds like thats the problem... a capacitor gone bad or something. I'd suggest you do the same.

Click Here to Read about this
 

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Did that and both ECUs act the same. I even changed my plugs and wires twice. My coil pack was upgraded to the CTC unit and my power transistor was replaced. I went with the idea it was the fuel filter and also upgraded to the supra pump. I even had the alt and batt tested and they are fine. Next I went to the timing and everything came back fine. I have also sealed up the pipes so its not leaking and I have also looked at the TPS and ICS.
 

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I have a similar problem as well and mine only happens at around 4000 rpms at full throtle. Not sure what to think other than maybe the throtle position sensor or fuel pump. I have changed the pressure regulator and the wires/plugs but it still does the jump thing so next week I plan on changing out the sensor and if that don't fix it the stock fuel pump is history and a better one will be put in (gonna need a better fuel pump for the bigger injectors soon anyway).
 

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Weed_Man,

Sorry, I read the post late last night. I missed the last paragraph that indicated in was only at 3400rpm. If that's the case than obviously it's an rpm-related issue. There are Supras that sometimes have the same problem and it is sometimes a throttle position sensor going/gone bad.

I doubt it's a fuel problem because that wouldn't be present at only a certain RPM, it would get worse as fuel pressure rises (with boost).

I would not reason out it being ECU related, either. It very well could be.

Ysofast:

Does your car miss only at a certain rpm? Or does it get worse as the rpm/boost increases?

-m
 

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Discussion Starter · #10 ·
Okay, well I dismantled the front of my car yesterday afternoon and got the ECU out... I can't wait to go through the fun of putting it back in! ;) I have yet to open it, but I am now more sure than ever that it is my ECU...

After checking all over on the web at DSM sites, and any other source I could find....

The 3 symptoms are:
1) a ticking noise coming from the dash
2) a seafood smell
3) an ECU that is 7 years or older that has experienced many temperature changes.

Okay, I HAVE experienced #1. At the time, I heard it coming from behind my SBC-iD and it eventually stopped so I forgot about it. It has happened since then.
#2, I haven't noticed, I think that would mean it was pretty fried, I don't think mine's that bad yet.
#3, I have a 1993... So its 9 years old. I live in Austin, so the temperature varies drastically on a day to day basis. Gotta love Austin! ;)

Anyway, I'll get my dad to help me take it apart in the next couple hours, and there is a computer parts store in town that I should be able to find the capacitors at. My dad used to build and race cars and before that he built and installed alarm systems and computers... I think he'll be useful to me here. haha :)

YsoFast, I truely hope I do not have the same problem as you. However, look at it on the bright side.. by the time you fix it, your car will be so upgraded you'll run 11's :D
 

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Discussion Starter · #11 ·
Marcus Frost said:
Weed_Man,

Sorry, I read the post late last night. I missed the last paragraph that indicated in was only at 3400rpm. If that's the case than obviously it's an rpm-related issue. There are Supras that sometimes have the same problem and it is sometimes a throttle position sensor going/gone bad.

I doubt it's a fuel problem because that wouldn't be present at only a certain RPM, it would get worse as fuel pressure rises (with boost).

I would not reason out it being ECU related, either. It very well could be.

Ysofast:

Does your car miss only at a certain rpm? Or does it get worse as the rpm/boost increases?

-m
Well doesn't the ECU control the fuel delivery? If the ECU is acting up, couldnt it cause the fuel system to act up?

YsoFast, did you straight up replace your ECU?? Or did you have it repaired?? Replacing that ECU from something like a used place or a salvage yard might not have corrected your problems at all. These go bad whether or not they're in a car... Clean up the board and replace the capacitors. Capacitors cost like $1.

Now though, they made the 2nd gen capacitors out of a different type of metal... Would it be possible to upgrade to a 2nd gen capacitor? Or would that pretty much fuck up everything haha
 

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Discussion Starter · #13 ·
News?

No not really... My dad inspected the ECU itself and theres no visable damage... No smell... I verified.. So basically, we'll replace the capacitors just in case and see if that fixes anything.

The computer place we would buy the capacitors from is closed on weekends. So no new news til tomorrow night? We'll see, I'm in no hurry at the present.

What else could it be if its not the ECU?
 

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I have the same trouble in the upper rpm's around 5000. mostly at WOT.
 

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"Does your car miss only at a certain rpm? Or does it get worse as the rpm/boost increases?" Well I replaced my FPR and still have the miss! :mad: The miss only happens at 4k and up at WOT or near WOT. If I slam on the gas at say 3500 rpm in 3rd gear it will pull fine untill around 4k. I am stumped!! I guess since I made it this far I should just replace the TPS even if I think its fine.

After thinking this was an RPM related problem. I slowed the car and put it in 5th gear at 2k rpm and this is what happened. I got the missing at aroung 3500k but the pause/miss was about 3 times as long. FIGURE THAT ONE OUT!!

A few weeks ago the car was running fine (for a day) and I notice after it went back to running like shit that my o2 readings only go to .95 volts but when it was running fine it hit 1.01 volts. Also after logging it on the TMO my TPS is only going to 80 and not 90 like it was when it was running correctly. :confused: Another thing is that while missing my O2 readings go crazy jumping around so fast I can't read it. If you guys have any input I am all ears. Either PM or post here.

BTW: My boost controler is OFF and this happens!!

I replaced the ECU because of a small burn mark on the old ECU. The new one I have is sealed and because of that I never opened it but how could to ECUs have the same problem. I guess I can have the old one sent out and repaired and even if that doesn't fix the problem I could sell it.
 

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Mine is just like yours, fly's but if I floor it around 4k I get shuddering. I am running upgraded turbos = to dr650 on stock injectors. Boost at 14psi but hit 15 yesterday. once I hit 15, boom, felt like fuel cut. i have also opened my ngk plats to .034 to fix a rich smoking condition. I will be doing the coil upgrade soon but the problem was with the plugs at .032 aswell. How much was the power transistor? That was my thoughts, but if it didn't work for you. I am lost, I need a logger!
 

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Bluv69k,
With your setup on stock injectors you are seeing fuel cut. I would upgrade and get am ARC2 or something like that. Your problem is a little different than mine because with my boost controller off I get this at 8psi with stock turbos. Your post is making me think my injectors are shot. I will have to look into that. Anyone know how I can tell??

This reminds me of the night before all the problems... I was running 14.5psi at arount 150mph and the next day this started at boost. SO I started turning the boost down more and more untill it stopped but now I get it missing with the boost controller off.

I will see is I can find that power transistor price for you but it wasn't cheap.
 

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well, did a little test today. I was going slow and left it in 2nd with around 15psi of vac. I slowly gave it pedal but not enough to build any boost. around 6000 rpms I could start to feel it again. not like under boost but it's there.
 

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Discussion Starter · #19 ·
Sorry about the delay... anyway, i'll try to fix it tomorrow. The last night I spent testing it, it always happened before I'd get to wot.. I would be at like 3/4 throttle and it would do it. Friend drove it too, same result. However, a few times he just let it rip and nothing happened. I never knew how scary it was to be in the passenger seat of a 3/S in the middle of a punch from a 10 mph roll... lol... the cars come and go on the right sooooo faaasstt ... :eek:
 

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Discussion Starter · #20 ·
Bit of other things to think about.....

Could a capacitor, after having slowly built up power in it suddenly release it if it's going bad? Seems to make sense to me....

I was reading war stories on a 1G DSM site, and he mentioned that he could tell his ECU was acting up because his car kept "hick-upping"... I mean, if my ECU isnt the problem... something's fucked up. ALL signs point to computer.
 
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