The 6th GEN Accord h22a project is running strong. I have developed an idle problem that I can't seem to figure out. It idles fine and steady, but when you hold an even throttle between 1000 and 1800 rpm, it surges. So when you drive through a parking lot and feather the throttle, the car lurches like crazy. The other thing I have noticed, is when moving and I let off the gas, it feels like I am missing a small section of the throttle, so goes from mid throttle to none without the smooth transition, as well as when I accelerate after coasting. I know everyone is going to say the TPS, but the tps voltage is set correctly. At idle I have .3 volts, and the range is .2 to .5. I'd appreciate any advice.

 

I thought the TPS was to have an idle setting of .48-.50, .30 would cause some problems.


Jason

 

I realize I left a crucial part of the story out. The car ran fine for about a month with the tps set where it is now. I was getting the car ready for a show and pulled some parts of the engine harness to reloom them, as the wires were still unloomed from the swap. As soon as we started the vehicle afterwards I noticed this problem. I know it is caused by something we did but I have been under the hood 4 times and cannot locate the problem. So .30 is too low of a setting? Because my manual states the above voltages to be correct.

 

All of my experiences have me setting the TPS between .45 and .5. Usually as close to .5 as I can get at that point in time.

Jason

 

Reset the ECU. It is most likely the IAC valve...If it continues to do it after that, unplug the connector on the Valve and see if that helps, if it does, you either need to clean the IAC, or replace it, or just don't run it and live with the CEL being on. Also, did you bleed the coolant system when you did the swap?

 

I don't understand what you mean about "bleeding" the coolant system. It's possible since when we reloomed the harness, we replaced coolant hose going into the throttle body. That would have added about 6 inches of air to the system. I understand how this would affect heating and cooling, but could you explain how this would affect my idle, and only at the low rpms?

 

I reset the tps, now reading .489 volts. Engine still surging between 1100 and 1900 rpms. This is getting really freaking annoying!

 

We ran the car with the radiator cap off to purge out any air that may have gotten trapped. The coolant was a little low but nothing to get heated about. After about 15 minutes of idle time, the thermostat still hadnt opened, though the temp gauge was reading normal op temp. So I idled a little higher and still couldn't get any coolant flow, even tho the upper coolant hose was hot as hell. We gently squeezed the lower hose and got some bubbles. The surging isn't as sever but still there. I think tomorrow I will pull the thermostat out and try it again.

 

Alright MackDad, I completely disassembled the trhottle body and intake manifold, cleaned thouroughly and replaced gaskets as needed. The IAC valve got cleaned as well. I also replaced the thermostat. Then bled out and flushed system for about 7 to 8 minutes. And dangit if that idle surge wasn't still there. Any other ideas?