Hey guys, I have a terrible idle problem with my car right now, which is an OBD1 B18C DA. I put it in this forum because it is boosted, I doubt it makes any difference with any parts, but anyways Ill continue. I tried to get the idle down...I have tried setting base idle (correct way, with IAC unplugged) to no avail...if it goes too low it just dies. Anything under ~1100 it dies. I plugged the FITV hole, no change so thats not the culprit. If I plug the IAC hole it dies, so thats good. No vacuum leaks. Checked throttle cable. Could it be in the tune? Any ideas? I have been trying to set ignition timing, and I assume it HAS to be at the factory 750 +- 50 rpms to be accurate, correct? There is no way to set it at my ~1100 or so, I assume. I really need to figure this out...

 

Oh also, with the TB screw in all the way, it still idles high....but no vacuum leak...what gives?!?!

 

what are you tuning with? Can you lock timing?

 

Jump the service connector, set base timing at idle to 15* BTDC in your low-cam ignition table, then use a timing light to sync table timing to actual.

If the tuning software you are using has IACV duty cycle control, play with that a bit.

If none of this makes any difference, you have a hardware problem (ie: vacuum leak, etc)

 

I only have a chip burner. But I am not familiar with tuning so I wont even try that, but thanks so much for the input. If the tuning somehow has affected the idle, is there any way at all to lower it? At least JUST to set timing?

 

If you've had the ECU tuned, all information here can basically be thrown out the window. Your tuner could have set the low cam maps to increase timing at any RPM or load point or have it a steady 16.5 until 1500 RPM at all idle loads. We have no idea without seeing the map, so really, nobody other than your tuner can suggest how this will work for you until we see it. If you had a completely stock ECU we could easily tell you what would work and what wouldn't.

 

I could post my bin file if that would help?

 

I'm sure someone would be able to take a look, but it sounds like you're on crome and I don't personally touch it. You could post a screen shot of the low cam timing table. If the screenshot includes the whole window it will say what base code, etc.

 

 

Ok, I can't be sure what code base that is because the lower portion of the window is cutoff (It looks like P30 based on the load scalars, but you can import different maps so it's hard to tell), but more than likely with the service connector set you'll be able to idle all the way up to 1250 rpm with at most a .5 degree variance away from 16.5.

For instance, with a P72 code base .25 is added over 1000 (16.75 total timing) and .5 is added above 1200 (17 total timing). Hope that helps.

 

At the bottom it reads "Advanced Boost Tools +P30 FV + Gear" so Im assuming P30 base...

With that said, and looking at the map, can you DEFINITELY say, if I am idling anywhere below 1250, it will be exactly at 16.5, correct?

So, basically, I idle under 1250, then jump the service connector, then using the gun set the timing to 16 degrees? Or should I set to 17, or what? And this is absolutely correct and safe? I want to be absolutely sure it is set right.

I really, really appreciate the help

 

And lastly, it IS 100% safe and correct to set the timing with the idle high BECAUSE of the code, is what you are saying, correct?

 

P30 likely functions the same, as they both have RPM based ignition corrections applied, so no, it won't be 16.50 up to 1250.

 

Sorry, I am a little dense...could you, using my above questions, please spell this out for me completely? I am sorry and i really appreciate the help, but you seem to really know this stuff, so I would like to know exactly what I need to, dont want to mess this up and want to know the correct way to do this...

 

Some Honda codes have a built in ignition scalar that is applied as a factor of engine speed. Basically, at 1250 RPM's at 400mbar, your table timing may be 16.5, but with the ignition scalar it is actually closer to ~21* BDTC.

You must disable this scalar to sync base timing. To do so you jump the service connector. This allows you to set the distributor timing to match the table timing without the Honda scalar applied.

 

Sorry, but jumping the service connector does not disable the RPM based ignition adjustments.



As I've already stated this is what you'll likely see...

I'm really not sure I can spell it out any further. I've given how much ignition timing is added, at what RPM, and the total overall timing you'll see based on the screenshot you've taken of your maps. I guess I could just give you direct points and spell it out.

From 0 to 1000 RPM you'll see 16.50 degrees overall timing with the service connector jumped.
Above 1000 RPM you'll see 16.75 (16.5 table + .25 RPM adjustment) degrees overall timing with the service connector jumped.
Above 1200 RPM you'll see 17 degrees overall timing (16.5 table + .5 RPM adjustment) with the service connector jumped.
And above 1250 RPM you're no longer running 16.50 table timing, so it just goes up from there.

To answer your question, no, you won't see 16.50 at the point you're asking about. At 1100 you'll likely see 16.75 degree total timing.

And yes, your idle situation is probably in the tune. I've had cars with no IACV idle lower than 1100.

Hope that helps. Good luck.

 

OK, so say Im idling at 1100. I would likely see 16.75 degrees total timing. So I then jump the service connector, and match ignition timing with the 16.75 degrees timing in the table, correct? Since I cannot match the .75 exactly, would it be safe to adjust for 16 degrees, or shoot for what would be 17, between the 16 and 18 lines (Fluidampr pulley)? Im pretty sure I understand the timing must match the table timing now, but Im unsure exactly how to get this 16.75?

 

Your ignition timing will be up and down until you jump the service connector. Then it will be 16.75 above 1000RPM and below 1200RPM. You could still shoot for 16, but of course you're a little less than a degree off. Or you can shoot for 17 and be .25 off in the other direction. THAT is up to you.

 

TPS min/max values?

 

Awesome. Of course, shooting for the lower end would be safer instead of going to 17, which would be .25 degrees advanced, correct? It would be safe to go for the 16 over the 17?

 

Yes, especially if you haven't had it tuned yet. And when you get it tuned, your tuner should be able to get the timing set correctly.

 

I think you should all take a step back and look at the overall picture. 1-3 degrees may matter with a basemap & no tuning, or on a previous tune on a 700hp beast. 1-3 degrees will not matter if you're tuning for optimal torque later on, and the engine has a different compression from stock.

In other words, the OP will have to change every cell a little anyways, since the motor is no longer the exact same configuration as stock.


I do agree with getting everything "just right"; however, I think the idle issue should be fixed first. I've heard some people have issues running code different from the IACV, such as P30 code (b16) with a P2P IACV (d16y8).

 

Tuning and the values of total ignition timing anywhere other than idle have absolutely nothing to do with the OP's question, which is about setting timing with a high idle. As I just stated in my post above it's better to set it more conservatively, especially if he's not yet tuned... and when he gets it tuned the tuner should be able to get the timing set correctly. That *is* the overall picture.

 

The car IS tuned already...dyno and street for part throttle. Just have the idle issue and need to time it correctly since I replaced a HG and took the dizzy off...

 

Awesome, the info still applies. Set it conservative until you are able to fix your idle and time it properly.