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Old 03-12-2013, 10:46 PM   #1
Soarer
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Default Motor only taking 16 degrees of timing, hesitation off cruise

Details: 1998 Legacy, EJ257 short block, B25 heads, STi cams not running avcs, JDM intake manifold, Bosch 1000cc injectors, VF43, 3" APS inlet, SPT intake, 3" HKS downpipe, Megan up pipe, 3" catless exhaust, STi TMIC, 2002 WRX ECU, Walbro 255 fuel pump, Grimmspeed EBCS, NGK Iridium 1 step colder plugs. I recently swapped this motor in. I upgraded it from an ej205. Before putting in the ej257, I put new head gaskets on and cleaned the pistons and combustion chambers so there are no carbon deposits.

Had Mike Botti tune my car last night and overall, it went well. I can't say enough good things about Mike. He really took the time to work on the car and get things as good as possible. I highly recommend him.

We ran into a few issues though that I'm looking for some help solving. The biggest thing that is bothering me is that the motor only took about 16 degrees of timing. Mike was saying that it should take closer to 20. We thought it could be a bad tank of gas so I filled up with Mobil super but it still did the same thing. It would knock with anything more than 16 degrees of timing. We have the car running 20.5 PSI. What are some reasons that the motor won't take more timing?

The second thing is that I get a hiccup when I accelerate off of cruise. If I'm putting along at 3000rpm in third gear and I start to put my foot down, the car will hesitate and then get moving smoothly into boost. Mike said that he didn't see anything in the data logs to pin the hesitation on. What are some things that can cause this?

I'm just starting to learn about tuning so forgive me if I'm a novice.
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Last edited by Soarer; 03-13-2013 at 12:37 AM.
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Old 03-13-2013, 11:52 AM   #2
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That hesitation sounds related to CL/OL transition, you might have him double check the delay values.
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Old 03-13-2013, 12:03 PM   #3
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Originally Posted by mechatricity View Post
That hesitation sounds related to CL/OL transition, you might have him double check the delay values.
+1 ^^^
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Old 03-13-2013, 01:50 PM   #4
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That's an excellent thought. I'll check with my tuner on that.

I also had a thought about my timing issue. If I were getting any oil in the intake tract, that would lower the octane rating of my fuel and make the motor detonate at earlier timing points, correct?
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Old 03-13-2013, 01:57 PM   #5
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That is correct, however, the timing issue could be related to your heads setup(just speculation).

I have found that there isnt a one size fits all timing curve for our engines so while you may think you are leaving power on the table, 16 degrees advance to redline is your sweet spot.
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Old 03-15-2013, 12:51 AM   #6
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Quote:
Originally Posted by mechatricity View Post
That hesitation sounds related to CL/OL transition, you might have him double check the delay values.
I'm sure Mikey has that under control. tip in is a possibility, but I have a hard time believing he would be too far off on tip-in either. Both of those would show clearly in a log via the AFR.

BPV leak would potentially cause the timing wierdness. It's really tough to pin down, since you can make boost and the leak goes back to the intake, so it doesn't really show in AFR either, it just makes the turbo work harder and since we don't have IATs in the manifold, you're a little blind to it. Wouldn't cause hesitation though unless it was a constant small leak... which a BPV leak usually is not.
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Old 03-15-2013, 12:52 AM   #7
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I also had a thought about my timing issue. If I were getting any oil in the intake tract, that would lower the octane rating of my fuel and make the motor detonate at earlier timing points, correct?
That's true, but that kind of thing is usually not consistent. Blowby is not a gradual thing, it happens in spurts ... on / off irregular frequency kind of thing.
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Old 03-15-2013, 09:23 AM   #8
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Gentlemen, first of all, thanks very much for the input. It is greatly appreciated.

After driving the car about a hundred miles since the tune I'd like to more fully describe the symptoms. When I am cruising out of boost, it drives fine. When I begin to get into boost, usually starting at about 2900rpm + or - 300rpm, it feels like I've hit a flat spot. The car stumbles along as the boost levels are between 1 and 10 psi. Once boost goes above 10psi, she pulls hard. This whole issue is particularly annoying because during casual driving, the car wants to be in the 2600-3600 rpm range making low boost levels which is exactly where the problem is. To drive the car smoothly now, I need to avoid boost or get deep into it.

I will investigate the BPV (bypass/recirculating valve) possibility. I'll check for leaks and I've got a few spares on the shelf.
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Old 03-15-2013, 09:28 AM   #9
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I should also mention that a CEL code p1443 just popped up for evap control solenoid valve. I don't believe it's related as it happened with the last motor too and the chassis has 180+k on it.
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Old 03-15-2013, 10:20 AM   #10
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Did Mikey have a wideband in place while tuning?? Sounds like the motor is loading up with fuel as boost comes on...
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Old 03-17-2013, 07:52 PM   #11
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Quote:
Originally Posted by Concillian View Post
I'm sure Mikey has that under control. tip in is a possibility, but I have a hard time believing he would be too far off on tip-in either. Both of those would show clearly in a log via the AFR.

BPV leak would potentially cause the timing wierdness. It's really tough to pin down, since you can make boost and the leak goes back to the intake, so it doesn't really show in AFR either, it just makes the turbo work harder and since we don't have IATs in the manifold, you're a little blind to it. Wouldn't cause hesitation though unless it was a constant small leak... which a BPV leak usually is not.
+2 for checking tip in
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Old 03-18-2013, 05:20 PM   #12
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Did Mikey have a wideband in place while tuning?? Sounds like the motor is loading up with fuel as boost comes on...

I installed a wideband. AEM UEGO.
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Old 03-18-2013, 11:27 PM   #13
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Been giving this problem a lot of thought and figured I'd try a few things this last weekend. Had a hunch that I could be a spark issue. Had a spare set of coil packs on the shelf so I figured I'd check the plugs, do a compression test while they were out and swap in the other set of coil packs. Plugs all looked a nice light brown and were gapped correctly, compression was good on all four cylinders. New coil packs installed and after one test drive, I think my problem is solved. More driving will tell but for now, I think the hesitation issue is gone. I'm curious if the motor will take more timing now. Will find out later this week when I meet up with Mike again for a tuning session.
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Old 04-03-2013, 01:45 PM   #14
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Unfortunately, the hesitation is still there. I need to figure this out because it makes daily driving uncomfortable. It's pretty strange to me. I'm going to meet up with Mike again on Tuesday and I'll get him to email me some datalogs of our session.

Once again, my issue is that when I'm doing regular driving (not driving hard at all, just going through the gears normally) and the motor is between about 2350-3700rpm and between 0-12psi, it doesn't run right. It's like it stumbles through. If I give it more gas and the boost comes about 15psi, it pulls strong and feels good. I am also getting a small backfire during regular driving occasionally. When I watch my AFR meter, it seems to stay at about 14-15 under light boost. When I get into higher boost levels above about 15psi, the AFR comes down into the 12-13 range.

I'm thinking that there could be tuning reasons and there could be mechanical reasons. What are some possible tuning causes for this?

What are some possible mechanical/electrical causes for this? I'm thinking it's probably a mechanical issue because Mike didn't see anything in the logs to point to a tuning issue.
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Old 04-03-2013, 01:51 PM   #15
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Unfortunately, the hesitation is still there. I need to figure this out because it makes daily driving uncomfortable. It's pretty strange to me. I'm going to meet up with Mike again on Tuesday and I'll get him to email me some datalogs of our session.

Once again, my issue is that when I'm doing regular driving (not driving hard at all, just going through the gears normally) and the motor is between about 2350-3700rpm and between 0-12psi, it doesn't run right. It's like it stumbles through. If I give it more gas and the boost comes about 15psi, it pulls strong and feels good. I am also getting a small backfire during regular driving occasionally. When I watch my AFR meter, it seems to stay at about 14-15 under light boost. When I get into higher boost levels above about 15psi, the AFR comes down into the 12-13 range.

I'm thinking that there could be tuning reasons and there could be mechanical reasons. What are some possible tuning causes for this?

What are some possible mechanical/electrical causes for this? I'm thinking it's probably a mechanical issue because Mike didn't see anything in the logs to point to a tuning issue.
Have you adjusted tip-in for your injectors? Kinda sounds like a tip in issue but you would see when you step on the gas it going either lean or rich.
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Old 04-03-2013, 02:37 PM   #16
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Have you adjusted tip-in for your injectors? Kinda sounds like a tip in issue but you would see when you step on the gas it going either lean or rich.
I would imagine that Mike did but I will check with him. What else should I check?
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Old 04-18-2013, 04:28 PM   #17
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Would a vacuum/boost leak cause these symptoms?
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Old 04-18-2013, 08:00 PM   #18
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i ran into a similar problem when tuning a 2.0 with 272 cams, 49lb wheel, fmic, 850cc, fp
the usually goodies to support a 49lb turbo.

had to tweak the maf table to get the stumble/hesitation to go away.

which cam sprockets did you use?

but the timing issue is odd. the factory timing for ej257 closer to 20~22
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Old 04-22-2013, 03:16 PM   #19
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I think I've isolated what is causing my hesitation problem. I did a boost leak test yesterday to find that my injectors are leaking at the seals where they go into the intake manifold. I'm running a v8 long runner JDM manifold with adapter plates to use USDM fuel rails. The injectors are Bosch 100cc and have all new O-rings on them. It seems that the adapter plate is about 1mm too thick which is spacing the injectors a little too far away and not pinching them into the manifold tight enough. 3 out of 4 injectors were leaking under the boost leak test at 7psi. I'm thinking that I'll just swap back to a USDM manifold and do a TGV delete. At least that way I'm confident I can get the injectors to seal.
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