Hello All,

This is my first post to a forum that has helped me immensely by searching the forum for my Honda, but this is the first time I have a problem that needs more help.

Here are the details:
96 Accord, 150K miles, purchased at 60K with blown head gasket. Had a shop machine and replace the head gasket, and have had 90K trouble free miles.

Last week, I had a CEL 71 code, misfire of #1 cylinder. On closer inspection, I found a bad intake manifold gasket leak from #1 cylinder. I cleared the code, and drove the car for about 200 miles, but the car began idle surging at about the same time. I decided to change the intake manifold gasket this morning.

The gasket was badly deformed near #1 (installed incorrectly by shop that did the head gasket), so I R&Rd the intake manifold with new gasket. Bled the cooling system, and started the car. Car started right up, and idled at high idle until it warmed up. I forgot to plug in the TPS plug, cleared the code, and started it up again. Now with the engine warm, she won't idle. The idle drops down to below 500 rpm, and stalls. I double checked for vacuum leaks, and open vacuum lines, but found nothing wrong.

I'm not too familiar with working on Modern cars, but I'm letting the car cool down to see if she'll idle when it's dead cold. Are these computers smart enough (dumb enough) to set the idle incorrectly with the unplugged TPS?

Sorry about the long post, but I've got the weekend to figure this out so I can drive my car to work on Monday!

Thanks in advance.

Tom

 

Air in the coolant can cause idle problems. Also, cleaning and tightening the FITV can help (see first part of the FITV thread in the DIY section)

To bleed the system. When the engine is cold, open the radiator cap, and loosen the bleeder valve (12mm deep socket required) on top of the thermostat. Fill radiator with coolant until all air spits out and a steady stream of coolant comes out of the bleeder valve. Close bleeder valve. Top off radiator. Reset ECU by pulling 7.5 amp radio/backup fuse for a minute. Start car and allow it to reach operating temperature.

 

Thanks PAhonda.

I'll try both suggestions. I hate fixing something only to make it worse!

Tom

 

Is the Temperature sensor plugged in

 

Hi Chris,

I'll check. I need to first identify all the parts under the hood!

Tom

 

I think on your Honda it is below and to the left of the dist. I don't think you would remove it for an intake gasket job.

 

Hi Guys,

O.K. This is what I discovered this morning. I checked the bleed screw and coolant came out when I loosened the bleeder. I also removed the snorkel to the throttle body to check the FITV operation. She started right up from cold, but when the thermostat opened, the engine started to idle down and stall. I can feel suction on the FITV port inside the TB, but plugging it up with my finger still does not allow the engine to idle to keep running so I'm not sure if I'm eliminating it as a suspect. I can feel the coolant pipe leading to the FITV getting warm, so I'm assuming coolant is getting to the unit.

I also tried messing around with the idle setting screw just to see if I could get it to idle with my finger on the FITV port, but there's no difference. I know the proper way is to unplug the IACV, but I'm trying everything!

Should I remove the FITV to see why it's not closing when warm? Could it be several things acting in unison to cause my problem?

Your comments are greatly appreciated.

Tom

 

Now that you fixed the vacuum leak, and after you tighten the FITV, you might have to set your BASE idle. I'm pretty sure there's a write-up about doing that somewhere around here.

Maybe a mechanic mis-adjusted something to make it work with the vacuum leak.

 

I'm not out of the woods yet.

I got the car warmed up pretty well, and the vacuum from the FITV is a lot less than when it's cold, but I can't get the engine to idle.

I followed the directions on the DIY section for setting base idle, and no amount of adjusting seems to get the car to idle without applying throttle. With the IAC plug unplugged, I can't get the car to run lower than 1200 rpm when the car is warm. I even tried taping over the port leading to the FITV and nothing changed.

I'm trying to think this thing through,

1. Car ran O.K. before I pulled everything apart to change an intake manifold after blowing a CEL 71.
2. found deformed gasket on #1 cylinder, R&Rd intake gasket and steel gasket on TB.
3. Engine fired up immediately after everything was reinstalled.
4. once everything warmed up, the engine idled down too low to keep idling.
5. bled system, no change.
6. On day two, I fired up the engine from cold, and found FITV is slow to respond, but can feel coolant circulating to the unit.
7. I'm hesitant to remove FITV since I didn't have a problem with it before the intake gasket. plugging up the FITV port with my finger while its running does not help.
8. Can't get base idle up using adjustment screw on TB with IAC connector unplugged.

Here are some thoughts that I would love to get some feed back:
1. could I still have a vacuum leak? I've looked and looked. Sprayed carb cleaner and can't see or hear anything. The old vacuum leak was really bad, and yet the car seemed to idle fine, so I can't understand the problem.
2. Wouldn't a vacuum leak show up when the car is cold as well? The car seems to run normally during warm up. Problems only start when things get warm.
3. Looking for more sources of vacuum leaks on the manifold, is there any place I'm not seeing? There are a couple of small ones on the other end of the TB from linkage side, the PVC valve. Any others?
4. Another thought is the EGR system, but again, no suction from spraying carb cleaner.
5. I think the clue is something is happening when the engine reaches operating temp. It also seems to run rough when warm as I try to idle down the throttle at about 1000 rpm. (EGR?)

I'm determined to get this right!

Thanks everyone.

Tom

 

Check that the throttle and cruise control cables aren't stuck in the clip on the throttle body. I remember a plastic on the cable that got caught in the bracket. It caused my car to idle high all the time though.

Also, reset the ECU by pulling the radio/backup fuse. Start the car and see if a check engine light comes on. The short that connector and check for codes to be thorough.