Scan tool for '98 Forester? Issue Fixed.

[wtdash]

Hi,

I'm trying to tune my '98 Forester w/a Greddy Emanage Ultimate Piggy-back system after installing a turbo along w/other supporting mods....it is connected to the stock ECU.

 

Whenever I get to 4800-ish RPM the car starts to stumble and run poorly and if I keep my foot in it throws Misfire codes on all 4 cylinders. Otherwise, the car runs well.

 

I was @ tuning shop this weekend and the tuner's software didn't go back far enough to read what the ECU was doing in real time, so we couldn't figure out what it might be doing/seeing to cause it to misfire.

 

Is there anything I can use to see what the ECU is doing in 'real time'?

 

Background info:

 

Here's the good news from yesterday's Dyno tune in Arlington, WA (near Seattle) - I'm in N. Idaho:

1. About 230/230 @ 13 psi.

 

My goal was 250/250 @ 18psi - maybe even 20psi- which we almost reached @ just 13, so there's a possibility I can see 275/275.

 

2. The car cruised over and back mostly trouble-free. It threw the Misfire code climbing the pass on the way over, even though I tried to stay out of boost.

 

Bad News:

 

1. Couldn't duplicate it consistenly. Most of the time the car would hit about 4800 and misfire and fall off.

2. We replaced plugs , gapped by Dom (tuner) to .030 - No Change- (I had put 300 miles on mine getting there w/out the correct tune so we thought 'maybe' that was the issue)

3. We disconnected the EGR vac lines - Dom thought there might be an issue - No Change

4. We changed my vac lines as the pressure sensor (the one that connects to the stock map sensor) was on the same vac line as the stock Fuel Press. Reg.. - No Change.

5. We gave up @ 5p.m. after starting @ 10:30a.m. :-(. (Dom had numerous other customers show up - busiest Saturday he's had - so we worked on it intermittently.)

 

The car runs/idles better (not perfect), but whenever I get to about 4800 RPM, it starts to stumble and if I keep my foot in the thottle it throw the CEL for 'misfire' on all 4 cylinders....plus occasionally I get the P0420 Catalyst System Efficiency Below Threshold which is probably just a secondary code due to the Misfire. Since my car's ECU is old, Dom couldn't 'read it' real time to see exactly what, if anything, the ECU was doing to cause the misfire. His scan tool is only '99+.

 

Dom says it's most likely electrical/electronic vs. mechanical. The AFR's were fine right up to the point of failure...it's like something in the ECU says "No More" and causes the misfire, but Dom really didn't know what to check.

 

 

Thanks

Todd

Edited September 5, 2010 by wtdash

[porcupine73]

Well I'm sure the Select Monitor can do that.

[GeneralDisorder]

Start simple - plugs and wires. Turbo's do NOT like old plugs/wires - especially if the gap is wrong or worn away. You are getting misfire's right where the turbo should be comming online - which is indicative of high cylinder pressure's not allowing the spark to jump.

 

GD

[wtdash]

Start simple - plugs and wires. Turbo's do NOT like old plugs/wires - especially if the gap is wrong or worn away. You are getting misfire's right where the turbo should be comming online - which is indicative of high cylinder pressure's not allowing the spark to jump.

 

GD

 

Plugs were brand new and gapped per the Tuner's recommendation - .030. Wires aren't new but only 1-2 years old.

I should've included that info in the OP. Please see above.

Edited August 30, 2010 by wtdash

[THAWA]

.030 seems awfully small of a gap to me. Why so small? I'm not saying that's the problem, just that seems like quite a jump from stock. What plugs are you using?

[wtdash]

.030 seems awfully small of a gap to me. Why so small? I'm not saying that's the problem, just that seems like quite a jump from stock. What plugs are you using?

 

 

This was recommended by a couple of tuners and is close to the stock WRX gap. I believe the stock EJ22T is same as the NA @ .044, but w/the higher boost levels (~18 psi) I expect to achieve, I was told to narrow the gap.

 

Currently running the BK6RE; Had the PFR6B (JDM EJ20) in before.

 

Thanks

[Fairtax4me]

.030 seems awfully small of a gap to me. Why so small? I'm not saying that's the problem, just that seems like quite a jump from stock. What plugs are you using?

High compression (when under boost) makes it harder for spark to jump the gap in the plug. Results in misfires, and increases the chance of detonation (which is VERY bad when combined with forced induction). Two ways to get around that, narrow the gap, or get a high energy ignition system. Guess which is easier and cheaper (and more reliable) to do?

 

You definitely need some software that can monitor real-time data. This sounds like a MAF sensor issue (if it has one) but it could be anything.

[Allpar Mod]

If you're looking for a tool which does monitor real time data, look at the Innova Can I-II or the Can II scan tools. I have the model which does both generations of OBD systems. I purchased it through Amazon.com where I got the best price around, about $200. The Can II is cheaper. They are sold at a lot of retailers also. The real time mode shows a lot of the systems and has shown itself to be pretty reliable. I know for a fact that they are Subaru compatible as I have used mine on my OBW when it was throwing a code a while back.

[wtdash]

This sounds like a MAF sensor issue (if it has one) but it could be anything.

 

 

YOU ARE THE WINNER.

 

I'm not clear on Why, since I can't log my MAF voltage, but I swapped in a WRX MAF, which can flow more air before maxing out, and the Misfire is gone!

 

Thanks for your and everyone else's input.

Todd