I just got my prelude back after having the motor rebuilt and the shop I had it fixed at is at a loss for what the issue could be. When cold the car will idle high aroud 1500-1700 RPM then when it reaches operating temperature the car will idle very rough at 400-600 RPM feels like it is misfiring. I have replaced the plugs and wires. The distributor has no carbon tracks, I am not sure where to look next any help would be greatly appreciated.

 

verify cam/crank timing? idle control valve clean? any check engine lights?

the cold idle sounds normal.

 

I took the car to a shop and had a compression test done, and it has 180 LBS. in all 4 cylinders. I can't adjust the timing on the vehicle it's controled by the computer. it is now showing a DTC P1399 code. I had him check the ICV and he said everything looked fine. The timing & balancer belts have been recently replaced when the motor was rebuilt.

 

im not talking about ignition timing, im talking about cam timing.

what is p1399?

 

I double checked the cam timing everthing looks ok. The code P1399 is a generic random cylinder misfire. Honda Recommended that it could be that the EGR ports are blocked or the valve clearances are out of specification. Does that sound right to you?

 

plenty of things can cause a misfire:

bad o2 sensor
bad plugs
bad plug wires
bad distributor
EGR ports clogged
bad gas
out of spec valve clearance
bad fuel filter
bad cam timing
among others...

 

I did a valve adjustment & the car runs great now. Thanks for the help.

 

A friend of mine has a similar issue. He has a rough idle between 400-600 rpm, and when he presses the gas from a stop the car bogs out/ shudders than starts accelerating normally. He drives a 1997 prelude sh. His mechanic spent 3 weeks on the car and couldn’t find what was wrong. Blake what do you think it could be?

 

Does the car just idle rough or does it throw any check engine lights? Is the car misfiring? Has he changed anything recently on the car?

 

Mine does that sometimes and I'm having a hell of a time figuring it out. I changed plugs, and dist cap./rotor. Mines a 93 though so I tripped the service plug and got CEL codes 10, 12, 14. I know the 12 is from the EGR on the Sk2 Intake Manifold, but could that misfire/bogging at 2-3K be from the IAT or IAC?

(I made a thread but so far no replies.)

Ryan

 

hes throwing 2 codes one for the map sensor and one for the idle air control valve, he changed both and the CEL came on again about a day after and has been on ever since

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by LukieLuc &raquo;</TD></TR><TR><TD CLASS="quote">hes throwing 2 codes one for the map sensor and one for the idle air control valve, he changed both and the CEL came on again about a day after and has been on ever since</TD></TR></TABLE>
He replaced the MAP sensor and IAC sensor & he is still throwing the same codes? Did he change out the IACV as well or just the sensors? Also when he installed the new sensors did he just clear the codes or do a full reset on the ECU?

 

sorry about thread jacking
but he just cleared the codes at autozone

 

I would try doing a full reset on the ECU. If that doesn't work take a multimeter and make sure the sensors are operating correctly. You will need a service manual to tell you what voltages they should be putting out.

 

I have a prelude that dosent hold idle when the car is warm, but when its cold it idles fine.....?

 

i gota 98 prelude n just did motor swap to another 98 h22a4 everything is fine running good but keep pulling egr n code 71 and 72 replaced egr vale twice and plugs and wires and tried fuel injector cleaner stil no hel anyone got any answers

 

Did you swap over all of your emmissions stuff? The egr adds unburnt hydrocarbons from your power stroke back into the intake manifold so that they can be reburnt. How is your timing? what kind of fuel are you running it could be a number of things.

 

I really don't understand how you people find these old threads, especially when it has nothing to do with your post...

However, you probably need to clean the actual EGR ports on the intake manifold. There are 6 little caps about 1/4" in diameter down by the injectors. You have to pull them out (drilling and a slide hammer of some sort usually), then clean them out well, then press in the new caps. There are a couple good write-ups on here; search and you will find them.

 

when people google search questions , alot of old forums come up

 

could also be the ecu , i kept getting a misfire and iac valve code , using a 99 ecu , i switched to a 97 ecu and no cel , even though car still misfires at idle , the 97 ecu is less sensitve