Hesitations during a pull

[himself]

I had started the Megasquirt conversion to fix a problem that seemed to originate from the air flow meter where once the car was warmed up that after a long drive or on a climb the car would lose all power and choke it's way along.

Everytime I got a new AFM the problem was fixed for about 3 months then it would start again so I pulled out the AFM and put in a MSnS system. Took me about 3 months to get it installed and running but it works. The wideband is currently not installed since we are still playing with basic tuning but this has not fixed the problem at all. Fuel pump works great, it's an after market turbo pump and brand new.

 

Anyone have this problem or know what may be causing it?

[mario_82_ZXT]

Clogged fuel pump inlet, screen, or filter, or clogged injectors. Sounds like it goes lean.

 

Of course this is just speculation unless you look at your plugs or get the WB running.

Mario

[mobythevan]

You've got a wideband but your trying to troubleshoot without it installed?

 

Install it and see if your going lean during the hesitations.

[himself]

According to the Megamanual and some people here we were advised to get the engine running and tune it as best as we could without the wide band first then put it in when we got it going fairly well.

 

We'll check the fuel inlet screen and the injectors next, if that doesn't do it then we'll put in the WB and see if that does fix it.

[mobythevan]

Everyone has their preferences, but I say install it and worse case it doesn't help you figure anything out. It has the potential to help with every part of the tuning that deals with air and fuel.

[TimZ]

Everyone has their preferences, but I say install it and worse case it doesn't help you figure anything out. It has the potential to help with every part of the tuning that deals with air and fuel.

I agree - why would you want to do anything else? If you aren't looking at the engine's response to your tuning, you might as well be changing jets in a carb.

 

The problem you mentioned first could also be fuel tank venting (or lack thereof), btw. In other words, if the tank isn't venting, you could be creating a vacuum in the tank which would make it harder and harder to pull fuel from it the longer you drive. An easy test for this is to loosen the fuel tank cap and see if the problem goes away.

[himself]

Hmm ,the fuel tank vacuum never occured to me. I had orginally replaced the old locking cap with a new twist on cap since the old one hung there rather loosely, the new one is exceptionally tight. I'll give that a try too, thx.

[WizardBlack]

According to the Megamanual and some people here we were advised to get the engine running and tune it as best as we could without the wide band first

 

I am aghast that the megamanual says that. Get it in and tune with it. I think the only thing they were trying to tell you with that (I hope so, anyway) is don't get carried away trying to nail each load cell perfectly until you have most of the map roughed in.

[himself]

Well we put the LC-1 WB in, wired it up according to the Innovtek manual and it does not even turn on.

Here's how the manual told us to wire the LC-1 (We have he blue box version)

 

Blue wire to ground

White wire to ground

Black wire of push button to ground

Black wire of LED to ground

(All 4 of those are soldered to the same ground)

 

Black wire of WB to the other black wire of the push button and the red wire of the LED

(Those 3 are soldered together)

 

Red wire of WB to 12v power source (We have it on the pink O2 wire of the MS ECU as the MS diagram said)

Brown wire of WB is wired to the fuel pump relay at pin 87 with a 10A fuse

Yellow wire is unsused and taped up

[himself]

Found out some of the colors were backward on the MS diagram and that the LED Innotek gave us was defective so now the WB works, well at least we were able to calibrate it so far. Here's how it is now set up:

 

Black wire of the WB into the red wire of the LED

Black wire of the LED into the black wire of the push button

Other black wire of the push button to ground

 

WB blue wire to ground

WB white wire to ground

WB brown wire to pink MS O2 wire (pin 23)

WB red wire into distributer relay for constant switched power (pin 87)

WB yellow wire still unused

 

Still have a slight problem with the ignition white wire with a red stripe having constant power instead of being switched. Added a cut-off switch to remedy the situation for now, might be permanent or temporary.

[mario_82_ZXT]

Which pink wire are you referring to? I don't see it.

 

From the manual:

a. Red 12V supply (You can use the fuel pump power source)

b. Blue Heater Ground

c. White System Ground (should be grounded at the same place as wire above)

d. Yellow Analog out 1 (Pin 23)

e. Brown Analog out 2 (You can use this for an air/fuel gauge)

f. Black Calibration wire (Leave it disconnected as you only need to calibrate it once, make sure it is taped off as it has to be an open air calibration, and you don't want it to try recalibrating accidentally with the engine running.)

 

The unit takes about 30sec to warm up to operating temp. You also have to change the output to 10:1 = 0v and 20:1 = 5v or else the a/f will be off in megatune (using the Logworks application).

 

Mario

[himself]

The pink wire is pin 23 on the MS board. In the Innovatek manual it was saying that the analog 2 should go to an ECU and the analog 1 to a gauge and siince I have no gauge we put the brown wire to pin 23 (the pink wire) on the MS ecu. Should analog 1 go to pin 23?

 

We started the car just a few minutes ago to watch as many gauges as we could to see what went wrong when the car hesitated and we found the vaccuum pressure went negative right as the car did its thing. Tried this a few times and then the 5A fuse blew on one of the injector lines.

 

We also couldn't tell if the WB was working other than my a/f ratio was really messed up. I couldn't get the WB programmer to connect to the WB do I couldn't set those above mentioned values you said to enter.

 

At least we know it is the vaccuum line now but we arn't sure where to start. Any ideas? All the lines seem to be ok, maybe the head gasket or manifold?

[himself]

The 10:1 and 20:1 settings, were those to be entered in Logworks or the Lambda Programmer?

 

I could not get Logworks to run at all, for som odd reason it could not connect to the same port that I've been using for MS.

 

The programmer did work and there was a setting area under analog 2 where I could set it to 0v at 10.1 and 5v at 20.1 but as for 10:1 and 20:1 I did not see anywhere I could enter those values.

[mario_82_ZXT]

In reality, it doesn't matter which output you use for what, as they are both programmable. The way they say in the manual is for if you have a stock ECU car that runs on a NBO2 and their fancy a/f gauge.

 

Anyways,

setting area under analog 2 where I could set it to 0v at 10.1 and 5v at 20.1

That's what you want.

 

You also need to reinstall MT if you haven't told it you'll be using the LC-1.

Mario

[himself]

My air-to-fuel is still messed up, probably since I have not taken the time to reinstall MT but that is not the main issue.

 

We have checked every vaccuum line on the car and capped them off one by one ans tested the car to see if it still hesitates and it does) and this is all the data we can find.

 

The engine idles at 700-800rpm with a vaccuum pressure of 19 in. Hg.

It hesitates at any RPM and any KPa but the higher the rpm goes the lower ourt vaccuum pressure gets until it goes negative around 4500 rpm. If the turbo happens to kick in the vaccuum has gone as low as -7 in. Hg but the car will not hesitate under boost only while driving up an incline or under any amount of pull.

When a hesitation does occur the vaccuum pressure goes all over the board.

[TimZ]

My air-to-fuel is still messed up, probably since I have not taken the time to reinstall MT but that is not the main issue.

 

We have checked every vaccuum line on the car and capped them off one by one ans tested the car to see if it still hesitates and it does) and this is all the data we can find.

 

The engine idles at 700-800rpm with a vaccuum pressure of 19 in. Hg.

It hesitates at any RPM and any KPa but the higher the rpm goes the lower ourt vaccuum pressure gets until it goes negative around 4500 rpm. If the turbo happens to kick in the vaccuum has gone as low as -7 in. Hg but the car will not hesitate under boost only while driving up an incline or under any amount of pull.

When a hesitation does occur the vaccuum pressure goes all over the board.

 

When you say "vacuum pressure -7inHg", do you mean that you are running ~3.5psi of boost? That's a really confusing way to refer to manifold pressure - too many negatives.

[himself]

No I didn't enter any boost values in, inches of mercury (in. Hg) is the value of the vaccuum pressure at that time. I don't think boost values can ever be negative.

[TimZ]

No I didn't enter any boost values in, inches of mercury (in. Hg) is the value of the vaccuum pressure at that time. I don't think boost values can ever be negative.

 

Just wanted to make sure - you mentioned 19in of vacuum at idle (i.e. no minus sign) and then talked about it "going negative at 4500rpm" and as low as -7in when the turbo kicks in, which literally implies boost.

 

So if you aren't talking about boost, what do you mean by "vacuum going negative"?

[himself]

If you read up a few we thought that we might've had a vacuum leak that was causing the hesititations of the car but we could find no leaks. Is having negative values of vacuum pressure normal operation?

 

I know that vacuum pressure doesn't stay constant but I thought it had some parameters it pretty much always stayed between. The manual says it should be between 14.9 and 15.5 in. Hg at idle. Our is at 18.8-19.0 which isn't too bad and it jumps up to 24 when we let of the gas pedal rapidly. What we noticed though was that if we got her going, that the faster we got the rpms the lower our vacuum pressure went until around 4500 rpms (without the turbo engaged) the vacuum pressure would drop below 0 and start recording negative values and start choking and sputtering.

 

Whenever the turbo kicked in the vacuum pressure always went below 0 but the car never hesitated. (We keep blowing the 5A fuse going to one of the injector lines when we kick in the turbo and go past 4000rpm, which is annoying but that isn't my main problem).

[X64v]

To disambiguate the situation, instead of saying negative vacuum and all of that, lets refer to it in relation to ambient pressure. Your idle is 18-19 inHg below ambient, which is good. You say in your most recent post the sputtering comes in when pressure passes through ambient and raises to pressures above ambient. For our purposes here, this can only happen when the turbo is making boost.

 

...the car will not hesitate under boost only while driving up an incline or under any amount of pull.

 

That is saying something else entirely. If you're not under boost (above ambient air pressure) then you're at 0 or below ambient air pressure. So, which is it?