hesitation

vypa · Post by **vypa** » Tue Jan 07, 2003 2:14 am

ok i have a 93 NA legacy 2.2 and my problem is that when i press the gas fully, not at 1/2 or 3/4 of the way down, just a WOT the car just has no power... bogs down completely, almost doesnt accelerate... i was thinking maybe because the ECU reset but it did this a bit before that. any ideas?

morgie · Post by **morgie** » Tue Jan 07, 2003 3:38 am

annnnndddddddddd another one ! welcome to the club buddy ! hahaha

more seriously, i am hunting that hesitation / lak of power since 4-5 months now ( not at full time ! )

that problem only shows up when i boost 9 or more PSI (depends on the temperature) and over 4000rpm... mainly in 4th and 5 .

what about you ?

entirelyturbo · Post by **entirelyturbo** » Tue Jan 07, 2003 4:11 am

I think there's a forum somewhere on the Internet called Hesitation Central BBS, and I'm an active member

! Many of us have had this problem...I am starting to think that the MAF sensors on these cars are below par, I've heard stories of sensitive knock sensors retarding ignition for some reason other than knocking, coilpacks are a problem...

I will be getting a coilpack very soon, I will be sure to post on how that turns out, and I have a junkyard MAF on right now, but it didn't run any better than my factory one so I think I'm having a different problem...

Anyone else that has had this problem and actually solved it?

ciper · Post by **ciper** » Tue Jan 07, 2003 4:23 am

"knocking on wood with both hands"

My car has ZERO hesitation. It has to be something that is either worn or clogged. We just need to figure out what does it.

entirelyturbo · Post by **entirelyturbo** » Tue Jan 07, 2003 4:30 am

Well, here's the deal:

Symptom #1) No matter what gear I am in, if I punch it, the car will jerk forward with authority; it shakes the gearshift and hard. But once it's done doing that, if you stay on the throttle, it just doesn't want to go anywhere.

Symptom #2) Let's say I'm driving along, and I just stop accelerating at about 4000rpm. Now if I punch it, it will really go somewhere...

Sounds electronic to me...

I have a new intake hose which I inspected thoroughly for clogs, my MAF sensor looks brand new inside, every last vacuum hose checks out...

If it's not electronic, could I have a exhaust clog?

vypa · Post by **vypa** » Tue Jan 07, 2003 6:46 am

seems to happen in all gears, any RPM but only when i put the pedal to the floor... its a 5 spd non turbo by the way....

teesaa · Post by **teesaa** » Tue Jan 07, 2003 10:19 am

Looks like the hesitation has to do with the throttle sensor...or the knocking sensor...so electronic...

The BIG trouble is, that the ECU remembers the conditions the hesitation occurred the first time - and replicates it every single time the ECUs wiew of the engine looks the same.

So, after each hesitation the ECU should be reset - but who wants to do that.

The same is with the fuel cut. When it occurs, even if the turbopressure is lowered, in the same conditions, it will cut the fuel again.

ciper · Post by **ciper** » Tue Jan 07, 2003 7:58 pm

Have you guys sanded the mating surfaces of the knock sensor with heavy grit sandpaper and use the latest revision of the sensor? What about running a tank full of 89 octane fuel then when near empty reset the ECU?

entirelyturbo · Post by **entirelyturbo** » Tue Jan 07, 2003 9:38 pm

I always use 93 octane until the price around here got to about $1.65 a gallon, then I said screw it, I'm goin to 89! But this tank of 89 is just about done, so I'll try that...

vypa · Post by **vypa** » Wed Jan 08, 2003 2:21 am

i had the feeling it might be electronic... anyone kno what to do to fix it? didnt seem to start until after the ECU reset... just try replacing the knock and throtte sensors?

morgie · Post by **morgie** » Wed Jan 08, 2003 8:20 am

1rst, i'll describe the words i'll use here (sory, i'm a frenchy so it is hard for me somethimes

)
- Hesitation : You are at 4000rpm, 2-3-4 gear, you push the gas pedal to the floor expecting the car to pull hard.. but it don't... just a slow acceleration... and while releasing the pedal , when boost goes down, you feel like if the car wants to pull harder.... like if at mid-throttle, 6psi of boost, the car pulls harder than at full-throttle and boosting 10psi !!

- Jerking : Little pulsations i can feel as i push the gas pedal, from a non-consistant engine ....

Ok so now with my story :

On my side, i changed the knock-sensor, complete exaust system (did a great improvement on turbo response! , and power) , spark plugs wires, spark plugs... nothing good.

Tried a properly functionning MAF and Coilpack on my engine, nothing good either ...

Something strange : Remove the bypass hose from the BOV and the car pulls great ! no more problem ! (nothing to do with the BOV, simply that Air is aspirated throught that hose, air not-calculated by MAF, so air/fuel get's leaner, easier to burn, paf no more probs at 10psi) .

My new clue : I always ran on 91 gas. Changed the plugs, gap 0.035, nothing good.. cars jerking sligtly and big hesitation. Changed gap to 0.030 as a mecanic recommended, nothing good. Changed the gap to 0.044 as people recommended, nothing changed... maybe a bit less of that jerking issue.... Tried some 87 gaz, DUH ! no more jerking !

it is strange to me cuz i rised boost to 10psi and i have to lower the octane ???!!?!?! seems strange

but i'm no mecanic and i know "Nada" about all that stuff... so i checked the car, took pics, read a lot ... and maybe i have a problem with oil !! l't seems to be a LOT of oil in my intake system... running the BOV disconnected and the hose just in front of the BOV for like 10km, and when i check the hose, there is a thin layer of oil on it !!

i also looked up closely to the pics of my engine i took, and maybe there is too much oil in that intake system !

look at this one wich shows the plastic thing connection to the turbo... look at how much oil there is there ! and even on the Wastegate actuator and the Coolan line around it ! ouff !

http://images2.fotki.com/v14/photos/1/1 ... IMG-or.jpg

With this one you can see the connection of the plastic thing with the throttle body... there again, lot of oil... And just bellow the "S" shaped, dual-tubed plastic thing, you can see the hose that comes from the Driver-side valve-cover, and again, lot of oil over it ...
http://images2.fotki.com/v14/photos/1/1 ... IMG-or.jpg

so i'll start with thaking all the intake appart, hoses, etc... and clean them.. then i'll see how things are gooing... but i fear that running that much oil in the engine may have created problems elsewhere ???? any toughts about that ??

i presume the car was never cleaned, it now has 152 000km on it.

other pics of my engine can be found there :
http://public.fotki.com/morgie/morgie/m ... ur_detail/

thanx for your help.

entirelyturbo · Post by **entirelyturbo** » Wed Jan 08, 2003 6:19 pm

Okay, my intake's clean except for PCV, which does not affect engine performance.

The octane issue, though. The more octane gas has, the longer it will burn. So the longer it will burn, the more you can advance ignition timing without fear of mechanical problems, and with advanced ignition timing, you can expect a HP increase...

Now, this is a dumb question, but are our ECU's smart enough to recognize higher octane gas and therefore advance timing? Probably not. The ECU knows not to advance timing as far as it will go until the knock sensor starts complaining...

Even if that is not the case, doesn't high-octane gas have special additives in it that keep the engine cleaner (freer of carbon deposits, etc.)? That's my alibi for always using 93 octane, but should I really put the cheap stuff in it?

Post by **Legacy777** » Thu Jan 09, 2003 3:19 am

Higher octane gas really doesn't burn longer. The octane rating refers to the amount of energy required to break down the molecules to start the combustion process.

Higher the octane, the more energy required to start combustion. That is why high compression and turbo engines usually require higher octane fuel.

ciper · Post by **ciper** » Thu Jan 09, 2003 7:29 am

Right, higher octane fuel will burn at the same speed and contains the same amount of energy for the same volume.

Our ECU wont advance timing beyond the factory baseline, BUT they will keep timing at the max throughout the range with the higher octance fuel.

If you could get a 3 dimensional dyno sheet, showing power related to rpm and throttle position you would see that with high or low octane most spots are equal, however certain places would dip with the lower octane fuel. Did that make sense?

Ive always used 91 in mine

entirelyturbo · Post by **entirelyturbo** » Thu Jan 09, 2003 4:13 pm

Oh, well, that's what the mechanics at my job told me...

I will say that I have put my last two tanks of gas in as 89 as opposed to 93, and I will say that, in very technical terms

, it actually seems to run better. I would think logically that it couldn't run better, I would think I'm just paying less for gas. They're both over the requirement, so I wouldn't think one would run better than the other...

It seems smoother, and runs a little more like a healthy engine, not necessarily any more power, though...

Maybe I'm dreaming things up, I don't know...

You know, most new engines require whatever the manual says. My uncle's friend had a Silverado which called for 87, he by habit always put 93, and screwed some stuff up, don't remember exactly what... I'd say ECU...

Post by **Legacy777** » Thu Jan 09, 2003 6:27 pm

Here's the thing......it actually does make sense that the car runs better on lower octane gas. It is setup to run a certain heat range. If you go and put higher octane fuel, the ignition and everything else has to work harder to ignite the fuel.

Unless you go and re-configure everything to run higher temps higher octane fuel is not doing you anything.

However.....i have found over years of putting all sorts of different brands and octane flavors in my car that the car seems to run the BEST on 89 octane. It doesn't really care for premium.....and it doesn't like 87.......I don't know why.........but that's been my experience with my car.

entirelyturbo · Post by **entirelyturbo** » Thu Jan 09, 2003 8:21 pm

Legacy777 wrote:Higher the octane, the more energy required to start combustion.

This makes perfect sense with what you just said "the ignition and everything else has to work harder to ignite the fuel" , so now I understand.

And I second your experience with 89 octane. Like I said I've run two tanks, and the car's never run better...

boostjunkie · Post by **boostjunkie** » Thu Jan 09, 2003 8:29 pm

Just a thought . . . I had an A/F gauge hooked up to my GT just to figure out what was goin on with the hesitation . . . The car would bog down at 5500rpms and then pickup again.

What I noticed was that the car was getting progressively richer and richer through the powerband (typical), but at the times the car bogged the A/F was reading VERY rich . . . I'm talking at the very edge of the meter!!! Right when the car would bog, the A/F ratio would go quickly to lean and then back to rich (although not as rich as before). I started to wonder whether the incident was caused by the car not actually burning all of the fuel that was being injected . . .

Not sure if that's valid or not*shrug*

Jason

entirelyturbo · Post by **entirelyturbo** » Thu Jan 09, 2003 8:33 pm

I see you've got a fancy 255 fuel pump, but I'd say depends on your injector output. Are they maxed out or what?

boostjunkie · Post by **boostjunkie** » Thu Jan 09, 2003 9:01 pm

The problems I described we characteristic of my 2.5GT that I traded for Adam's car (that I have now).

Yes, I have a Walbro, and I'm sure the injectors are close to 75-80% duty cycle, but I haven't encountered any problems so far.

entirelyturbo · Post by **entirelyturbo** » Sun Jan 19, 2003 12:10 am

Upon further investigation, I understand it might also have something to do with the TPS. I haven't touched mine, I've screwed up enough set-from-factory stuff already...

Possibility with these cars?

morgie · Post by **morgie** » Sun Jan 19, 2003 1:02 am

Why the TPS ? what is is influence in all that ?

Mark Ward · Post by **Mark Ward** » Tue Jan 21, 2003 2:20 am

I noticed in one of the photos, someone still had the old grey plug wires on. I had the same prolem with my 2.2T until I changed the plug wires. Problem was gone immediatly...

BTW - NGK Blue

Mark
www.rrunracing.com

morgie · Post by **morgie** » Tue Jan 21, 2003 11:52 pm

MArk : It's me ! It's me ! (pointing a finger up) .. huhu

those are grey wires, but they are "Bosh" wires, brand new.

Mark Ward · Post by **Mark Ward** » Wed Jan 22, 2003 1:54 am

Good!
I was worried

Mark

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hesitation

hesitation