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Discussion Starter · #81 ·
Understood. I should still pin out the K-Tuned adapter harness as well. They were assembled by human hands. Even though they have been consistent so far, it is possible that somebody hiccuped and crossed a couple of wires.

Guess I am on hold until the immobilizer bypass comes in.
 

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Discussion Starter · #85 ·
I spoke with our Hondata dealer, who suggested that I should check valve lash. If the lash is too tight, it can cause a weak vacuum signal, which of course is true. I doubt that the lash is tight enough to cause a problem because the engine idles so smoothly. But it has to be something, right?
 

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this sounds similar to the problem that i am/was dealing with, but the map sensor i just installed today seems to have fixed the problem. my car would feel like it was hesitating periodically at a constant cruising rpm/speed, then when I would go wide open throttle or even partially open it would start to buck. It also had a fluctuating rpm while warming up and while idling (it wasn't constantly doing this but periodically). When i would approach a stop and put my car into neutral the RPMs would flatten out at 2k and only after a came to a complete stop would it fall down to around 1k and steady out. I do have a check engine light for my "AIR/FUEL SENSOR" so I had changed my primary 02 sensor like 6 months ago but shouldn't have had to because i had changed it like 1-1.5 years before that one. When i changed it the second time the check engine did not go away though, and even after i put the map sensor in today it hasn't shut off but i haven't check the code again (will tomorrow). When i previously looked at the parameters in hondata: the A/F would usually be in the high 20's (like 27-29) which should be lean but the exhaust usually smelled like gas, the MAP was also around -17 around idle and i believe 2 WOT.

SOrry if this didn't help hopefully it does,

D
 

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Discussion Starter · #87 ·
Received the K-Tuned Immobilizer Bypass. Installed with stock A2 ECU.

I am using my father's Mac Tools code scanner, which is more feature rich than ours here at the shop and since I no longer have access to the datastream in Hondata with the stock ECU.

The Mac scanner has a calculated load feature. At idle, this feature is reading 46%.

I don't know why, but the Mac scanner reads 10% throttle at idle. Hondata reads 1%.

I am reading MAP with key forward engine off at 98kPa--believable. Idle, once IAC is closed, reads 46kPa. That seems a bit high a pressure for idle, doesn't it?

Any credibility to the tight valve lash supposition?
 

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You are now making things more complicated.

Does the stock ecu stumble on tip in?

If you want to use the Mac scanner I suggest trying it on another car that is known to be running proper and using those results to compare too.

If you need to find out if the stock ecu is hookedup properly don't you need the 2ndary o2 hooked up? What about the multiplex?

An external wideband would be nice but wont tell you anything if the stock ecu is in limp mode. Back to what I originally suggested I think a stock 02-04 engine harness would be the best 1st step to figuring your problem out. Got one you can borrow from someone? Btw where are you located
?
 

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The Mac scanner has a calculated load feature. At idle, this feature is reading 46%.
On most every vehicle I've scanned load at idle was between 23-32%. On both my hondas they are 25-27%. Keep in mind, this is engine warm idle (650-800rpm, closed loop)

I don't know why, but the Mac scanner reads 10% throttle at idle. Hondata reads 1%.
different scanners/FMUs read relative/absolute TPS. both my hondas read 9.8% through the scanner, and 0% on my FMU

I am reading MAP with key forward engine off at 98kPa--believable. Idle, once IAC is closed, reads 46kPa. That seems a bit high a pressure for idle, doesn't it?
Yes, 46 does sound high for warm idle, from my experience, you should be sitting around 25-30kPa

Any credibility to the tight valve lash supposition?
Absolutely! exhaust valves tend to tighten up over time in k-series, and can attribute to similar/same issues you are having. If you don't have angled feeler gauges, it's worth the investment!
 

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Discussion Starter · #90 ·
Valve lash was tight, but not terribly. I found .006" or a little less on the intakes and .008" or a little less on exhaust. About to fire it up with KPRO re-installed and watch the datastream for changes.
 

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Discussion Starter · #91 ·
Drumroll, please...

Ready?

No change--exactly what I was anticipating.

Idle vacuum is very weak-- hovering in the mid 16" range of vacuum. I had held out hope that an egregiously tight valve lash could be causing the weak idle vacuum, which seems to be directly connected to the rich idle mixture. (See above posts in which I modified the MAP signal in KManager and got the idle right on stoich.)

This is all with the KPRO reinstalled, not the stock A2 ECU I tried out a few days ago.
 

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Discussion Starter · #93 ·
Have you tried a different MAP sensor?
You are using the stock K20Z1 TB with the stock flat front K20Z1 intake manifold right?
Yes, stock TB and stock IM. No apparent leaks anywhere in the intake tract. I used ye olde brake cleaner test. If I had a smoke machine, I would have used that.
 

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Discussion Starter · #94 ·
Interesting... 20-21" vacuum on an analog gauge.

I am hooking up another gauge right now.

The throttle is mounted on an extension necessary for clearance on this installation. I have used an extension on every car I have built. Vacuum ought to be the same across the entire intake downstream of the TB. I wonder if I might have siliconed a restriction into the MAP port.
 

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Discussion Starter · #95 ·
Confirmed 20-21" vacuum on two analog gauges.

That means a 4" discrepancy between the MAP reading in KManager and reading off the plenum from TWO analog gauges.

I need to close that discrepancy.
 

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Discussion Starter · #96 ·
Think I found it. The 02-04 TB is ported differently from the 05-06 regarding MAP. I was using 02-04 gaskets, which block off the MAP port. Putting it back together now.
 

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Discussion Starter · #97 ·
Solution!

This is as much for posterity as for you all in this thread.

The cause of the problem was a difference in porting for the MAP sensor between A2 and Z1 throttle bodies. I have a stack of new A2 TB gaskets, which I used on this car without even considering that there might be a difference in MAP porting.

The Z1 TB gasket must have a slit or a through-hole to the plenum allowing the MAP sensor access to changes in pressure. The A2 gasket lacks this slit or through-hole, so access to pressure was effectively blocked. Somehow, it saw SOME vacuum--enough to keep me from thinking until this week that there could be a blockage. The engine must have been pulling at the MAP sensor through the gasket paper. I am surprised that it got as good a reading as it did--16" at idle.

Thank all of you for helping me to think this through. I have learned so much about Hondata, the Honda management and differences in parts because of this problem. It's all about what you take away from the experience, right?

Thanks especially to Mike at K-Tuned. He spent hours on the phone with me helping me with Hondata and helping me reason through the problem--with nothing to gain. He even helped a great deal to fill in the gap for Hondata's atrocious attitude toward customer service. Thanks, Mike!
 
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