Low Timing and hesitation during cold start

[SiC]

I tested this out last night and this morning. I can confirm the problem is resolved, this is a big help for people with aftermarket injectors/cams. Now I don't have to avoid those RPM/load zones during cold start

Thanks alot!

[Hiboost]

Originally Posted by coevolve

Thanks man. The "axis" change post was the only thing that confused me a bit...
screenshots would be awesome. When did you start experiencing this low throttle condition? My X is stock save the tuning that i've been learning. My current part throttle is quite fine.

I noticed it on the stock turbo after doing some bolt on's but it was hard to feel the effect because I rarely ran -5 psi on the stock turbo at those low RPM's. With the larger laggier turbo that lower rpm range feels more "retarded" until boost kicks in to mask it. If you don't feel a hestitation at light throttle it probably won't matter. For me knowing the "how and why" it was doing the hesitation was the biggest thing.

[BigT]

i definately feel this on cold starts. i'll give it a shot tomorrow.

[coevolve]

Thanks Bryan/Tephra, got it:



I haven't exhibited problems with part throttle/cold start yet but it is still quite warm here and the car heats up rapidly....(NoVA)

I noticed it on the stock turbo after doing some bolt on's but it was hard to feel the effect because I rarely ran -5 psi on the stock turbo at those low RPM's. With the larger laggier turbo that lower rpm range feels more "retarded" until boost kicks in to mask it. If you don't feel a hestitation at light throttle it probably won't matter. For me knowing the "how and why" it was doing the hesitation was the biggest thing.

Thanks hiboost, that makes a lot of sense.

[tephra]

yeah i reckon it works as well

ok so the question is, do you damage the cat by not warming it up?

[Hiboost]

Originally Posted by tephra

yeah i reckon it works as well

ok so the question is, do you damage the cat by not warming it up?

I did some research last night on that topic, it's mainly just going to take slightly longer to warm things up for a cat to come up to operating temperature. The thing is if you drive at higher throttle to avoid the hesitation that yields 0 to 10 psi instead of -5 psi then you will be in the 100 to 140% load cells and not even have that table kick in very much. I'm going to test 40%, 30%, 20%, 10% in the columns to see if I notice a difference compared to 0%.

Since I am running 44* peak timing at cruising loads for better MPG, I would rather not run higher than stock 40* until it is closer to full operating temperature. We'll see where it sits, probably in the 30's which would be a good compromise.

[LaXGSR]

Thanks all for figuring this out! I was thinking about this. I tend to only notice the hesitation around 2000 rpm's, and only during the first 2 or 3 sessions of light acceleration from a stop. I think I need to log coolant temp during warmup to see how quickly temperatures rise. Since it doesn't seem to last very long, I don't know if I should modify these tables (or just leave it to help save the stock cat). Should I just deal with the annoyance or modify the tables? It's reassuring to know that it's not necessarily something wrong with my car (such as bad plugs), but it also sucks that the car just doesn't feel right under light acceleration after a cold start. Mine is most noticeable around 2000 +- 250 rpm's.

[tephra]

I did:
-32C 0
-8C 0
7C 100
20C 100
34C 75
50C 0
62C 0
77C 0

that seems to work quiet well, although im tempted to use 75 for the 100's as well..

[Hiboost]

Originally Posted by tephra

I did:
-32C 0
-8C 0
7C 100
20C 100
34C 75
50C 0
62C 0
77C 0

that seems to work quiet well, although im tempted to use 75 for the 100's as well..

I tested these settings and they were perfect for my setup:

-32 C - 0
-8 C - 40%
7 C - 30%
20 C - 20%
34 C - 10%
50 C - 0
62 C - 0
77 C - 0

That yielded timing in the high 20's at 2k RPM climbing to high 30's by 4k RPM with zero hesitation and coolant temps of around 120-140 F. Seems the temp scale is a bit off but the desired effect is working great and predictable.

Probably a less drastic change to test for cat users would be these settings which should still keep you away from dropping much below 20* in most cases and avoid hestitation:

-32 C - 0
-8 C - 75%
7 C - 60%
20 C - 45%
34 C - 25%
50 C - 0
62 C - 0
77 C - 0

If your cooling system is working correctly you should be warming the car up within a few minutes either way.

[BigT]

Thanks for posting this guys. Helped a lot!

[GSXR]

Originally Posted by Hiboost

I tested these settings and they were perfect for my setup:

-32 C - 0
-8 C - 40%
7 C - 30%
20 C - 20%
34 C - 10%
50 C - 0
62 C - 0
77 C - 0

That yielded timing in the high 20's at 2k RPM climbing to high 30's by 4k RPM with zero hesitation and coolant temps of around 120-140 F. Seems the temp scale is a bit off but the desired effect is working great and predictable.

Probably a less drastic change to test for cat users would be these settings which should still keep you away from dropping much below 20* in most cases and avoid hestitation:

-32 C - 0
-8 C - 75%
7 C - 60%
20 C - 45%
34 C - 25%
50 C - 0
62 C - 0
77 C - 0

If your cooling system is working correctly you should be warming the car up within a few minutes either way.

Thanks Hiboost!

I used 100%, 60%, 40%, and 20%. That was good enough for me and it worked great.

[Noize]

Sorry to bump a month old thread.

My car does something similar, but its different too.

I warm the car sufficiently before getting on the throttle, but I can drive normally for 15 minutes, than start accelerating in 5th on the interstate. When I pass through the 3300-3700rpm range, I feel hesitation. This is with the car seemingly warm, mind you. Its annoying enough that I'll replicate it a couple times, and it goes away completely.

Stock turbo, bolt ons. Thoughts?

I can try to capture the behavior in a log one morning, please tell me what parameters I need to log.

Thanks

[tephra]

coolanttemp/timing/knock/rpm/tps/load and afr if you have it

[Noize]

AFR I don't, but I know its straight from a dyno session recently. Low-mid 11s.
I'll work on getting the rest, thanks heaps Tephra!

[Noize]

.rar file renamed to zip to upload. Please change back to .rar to open.

I'm not getting any appreciable knock, nor does it seem to be acting funny on the road tonight. Its ambient 58 degrees F outside here, so quite cool.

Just wanted you guys to have a look to see what you thought.
I basically just cruised in fifth and booted it every few seconds in the range it sometimes hesitates, and held it.

Thanks for looking.