Appologizes for the double post, but I need the thread to get more exposure. The board is quiet anyway
So I filled up the fuel tank last night and started having some low end detonation trouble. I think I might be the victim of bad fuel. I also discovered that the J&S wasn't retarding timing with the check valve on its vacuum line, despite J&S telling me this wouldn't disable the knock detector in the unit.
Now the car is idling at 700 rpm. The car is pulling its normal amount of vacuum. The engine starts fine. When the radiator fan or air conditioning is on, the idle raises to the normal 800 rpm. When both are off, it drops back down to 700 rpm. The car is not smoking at all. I pulled the oil cap while the car was running, no smoke at all. Power seems fine. I'm having to pull alot more timing in the low rpm range since filling up with this tank of fuel.
I'm of course going to do a compression check right when I get home tonight.
Other than a blown piston, anyone have an idea of what might be going on?
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Last edited by sharkcohen : 02-09-2005 at 02:36 PM.
I'm not familiar with everything different about your car, but the idle numbers you listed are what the Helm's considers "normal" (~700 no-load, ~790 with electrical load).
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It's not normal, it normally idles at 780-800 rpm. It always has since I bought it new. And I'm pretty sure the 5th gen Helm lists the idle as such, although I don't have it with me at the moment.
i recently installed a vafc 2 on my car and mine idles at about 690-700 rpms does that mean i have some problems. The car runs fine no smoke or anything and i am NA. now i am worried too lol
5th gen idle speed specification (from the Helm's):
1) IAC valve disconnected & no-load conditions (basic mechanical idle -- this is what you should be using if you're adjusting the idle screw): 550 +/- 50 RPM
2) Normal idle, no-load conditions: 700 +/- 50 RPM
3) Normal idle under load (electrical load or AC): 790 +/- 50 RPM
I don't know why your idle is normally high Dave. Mine has been in accordance with the Helm's ever since I bought it new.
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try doing an idle relearn procedure on it. dont use the stupid throttle body screw like everyone always says. that only messes with iacv duty cycle.
now i know it may sound like b.s. but it isnt. if you have ever seen the term "driving cycle" used in the helms im about to tell you what it really means.
its absolutly insane actually. the "driving cycle" consists of an immense amount of data that the car accumulates through fuel trims, iacv duty cycle load variables etc. if you printed it all out on standard paper you would have enough to laminate a 6' x6' floor. i cant really go into detail about what all the data is because most of it appears to be jibberish to the common eye. but i somehow doubt the ecu would collect a bunch of b.s. for nothing. so a driving cycle isnt just 45 minutes or a half hour of driving or whatever.
if you do not do the idle relearn your driving cycle gets messed up from misc loads, trims etc. the computer basically doesnt know how to idle the car very well. i had stalling problems with my stage 2 crowers unrelated to my tight valve situation. i woudl reset the ecu and just start driving and the idle quality would degrade rapidly. when i finally took the time to do the relearn it has idled perfectly since. also, at the dealership they have to do this to every new car that comes in.
for anyone who wants to know how to do it, its very easy.
1 car off unplug the iacv
2 start the car,(it will get a cel for iacv, ignore it) it may die but keep restarting and eventually get it to idle.
3 it will idle low and rough but you need to check what the rpm is. with the throttle body screw adjust it so the idle is between 5-600rpm.
4turn off the car
5 pull the radio fuse to clear the iacv code you just had from having the sensor unplugged
now the idle is within spec of the iacv's ability to adjust it. by adjusting the base idle with the iacv disconnected your getting it into its range of operation so you dont max out its duty cycle.
now that the code is clear
6 turn on the car with absolutly no load, no ac, no lights no nothing
7 let it idle for at least a minute no more then a minute and a half
8 now turn on the headlights and let it idle for 1 minute
9 now turn off the headlights and turn on the a/c and let it idle for a minute
10 your done
5th gen idle speed specification (from the Helm's):
1) IAC valve disconnected & no-load conditions (basic mechanical idle -- this is what you should be using if you're adjusting the idle screw): 550 +/- 50 RPM
2) Normal idle, no-load conditions: 700 +/- 50 RPM
3) Normal idle under load (electrical load or AC): 790 +/- 50 RPM
I don't know why your idle is normally high Dave. Mine has been in accordance with the Helm's ever since I bought it new.
Have you ever run through the idle adjust procedure in the Helm's? Since you have an OBDII scanner, it's a piece of cake to read the RPMs during the adjustment steps and of course, you can reset the resulting IAC CEL just by pushing a button.
EDIT: I should mention that I did have to do this procedure once on my car. My car, which had always idled fine, started doing the bouncy idle thing after I had removed and reinstalled the throttle body while doing other work. After the idle adjust procedure in the Helm's, it was fine.
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Last edited by crashandburn : 02-09-2005 at 08:14 PM.
Open the Helms manual to page 11-115.
Follow instructions.
Close the Helms manual.
For some reason this post makes me hear "...then lobbest thou thy holy hand grenade...".
plnoldrick's description is pretty close. Steps 1-5 are pretty much what the Helm's says with the exceptions of a) you would probably be better off disconnecting the IAC with the engine already idling as the Helm's states, and b) 500-600 is indeed the acceptable range but 550 is the preferred target. Steps 6-10 are not any magic learning formula -- they are the setup parameters that you are then supposed to verify correct idle speed at each of those steps after you've set the base idle in steps 1-5. That is, idle speed should be 700 +/- 50 RPM after step 7, and it should be 790 +/- 50 RPM after step 8 and also after step 9.
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Steps 6-10 are not any magic learning formula -- they are the setup parameters that you are then supposed to verify correct idle speed at each of those steps after you've set the base idle in steps 1-5. That is, idle speed should be 700 +/- 50 RPM after step 7, and it should be 790 +/- 50 RPM after step 8 and also after step 9.
actually im going to have to disagree on that. setting the base idle is obviously the BASEline but the ecu also needs to write in how to shift the iacv duty cycle to deal with different loads like headlights and air conditioning. so basically it is a learning formula of sorts. it shows itself clearly in the driving cycle information if the idle learn isnt done on the car. granted the ecu does have its base enrichment percentages for idling with headlights or a/c but its also subject to enviroment like fuel trims so it needs to be set initially.
there is a lot more data on this stuff that is not in the helms manual. i'll see about getting my buddy to print out the advanced diagnostics stuff from honda.
Same...I put the VAFC on rev monitor and it dipped into the high 690's a couple times, but mostly right at 700 without load, and when the A/C compressor kicked on it would hit 800
actually im going to have to disagree on that. setting the base idle is obviously the BASEline but the ecu also needs to write in how to shift the iacv duty cycle to deal with different loads like headlights and air conditioning. so basically it is a learning formula of sorts. it shows itself clearly in the driving cycle information if the idle learn isnt done on the car. granted the ecu does have its base enrichment percentages for idling with headlights or a/c but its also subject to enviroment like fuel trims so it needs to be set initially.
there is a lot more data on this stuff that is not in the helms manual. i'll see about getting my buddy to print out the advanced diagnostics stuff from honda.
So you're saying that if you do steps 1-5 but not steps 6-10, then your idle will start messing up later? I'm pretty sure I've reset my ECU many times without doing steps 6-10 and I don't recall seeing any places in the Helm's where it tells you to do 6-10 after every ECU reset. Why would the ECU have to "write in" anything -- all it has to do is look at the actual idle speed, compare with the desired idle speed, and adjust the electrical current through the IAC accordingly. This is something that it should be doing continously anyway.
I would be very interested to see any "extraHelm's" material you can get on this...
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there is a lot more data on this stuff that is not in the helms manual. i'll see about getting my buddy to print out the advanced diagnostics stuff from honda.
Old thread, but did you ever get that data. I'm really interested.
has anyone else tried this and does it actually work? my car is stalling when it's cold for no reason. it will rarely idle. ill try this when i get a chance
I just tried this procedure because my lude's been idling in the 600rpm area and shaking, and even though my baseline adjustment was way off and I corrected it, im still idling around 600rpm. Turning on the headlights or AC however gets me idling at around 700 and the car feels smooth with very minor vibrations. Anyone have any clue my im still idling so low and with the shakes?
