Joey Mitchell

Plz help!!! My 98 Civic with the d16y7 will not stop surging at 1500-1600 rpm. It started a few months back, I had a bad water pump leak and I suspected the surging had something to do with my iacv. I've since deleted my iacv, replaced my water pump and timing belt. Still the surging presisted. I've now replaced my pcv valve, tps sensor, spark plugs, and I've checked for vacuum leaks using electrical cleaner in a spray can... Yet still the engine still surges/jerks between 1500-1600 rpm and feels kind of sluggish. I'm going to replace my distributor and plug wires tommorow, as I have a 92 ex d16z6 donor car. I'm hoping this helps but I'm kind of doubting it.. does anyone have any other ideas as to what else could possibly be causing the engine surge??? Plz help I'm almost at my witts end with this issue!! Thanks!!!

Joey Mitchell

Quick update, after posting this I went to mess with my idle screw, only because I have low idle due to my iacv delete, and it seemed to kind of help the surging issue. It's still there however, maybe not quite as bad, but I don't think it has anything to do with the idle screw being as the surge isn't happening on idle, it's at 1500-1600 rpm. Just wanted to throw that out there. Again, thanks in advance any help is much appreciated!!!

DaX

iTrader: (1)

Does the D16Y7 have a FITV? If so, I'd look check the adjustment on that.

Joey Mitchell

The FITV was located on the backside of the iacv, so it also has been deleted from my TB.

tony_2018

huh?

Joey Mitchell

The fitv is attached to the iacv, which I deleted. I reset my ecu this morning which I haven't done in a long time.. the problem seems to be better now, I can't get the engine to surge while in gear which is good, however when not in gear or when the clutch isn't ingauged it still surges slightly at 1500 rpm. Just enough to still agaggrivate me, I've got to resolve this issue.

mk378

If it could run properly without an IACV, Honda wouldn't have spent the money to put one on every Civic.

When my IACV failed, it was of course not idling well, also it was really hesitant and jerky taking off from a stop or putting along in slow traffic in first.gear. So I did the obvious thing and replaced the IACV with a good one.

JRCivic1

At really low throttle blade angles, the IACV provides a portion of the air flow needed to operate the engine up to about 2500 rpm. Deleting the IACV will cause the hesitation/jerky operation at low RPM.

So OP, why did you remove the IACV ??? Also, the FITV is a mechanical idle up device that is found bolted to the bottom of the T/B on a '92-95 Civic or '94-95 Integra. '88-91 Civic/CRX's have the FITV bolted to the intake manifold UNDER the T/B. How about posting a picture of your intake manifold and how you deleted the IACV and FITV.

tony_2018

Which was why I'm confused at why he said he had an FITV unless the throttlebody is from the 92-95 civic/94-95 integra.

Joey Mitchell

These are photos of my iacv. I was mistaken, the 2nd photo shows what I thought was a FITV, but it's just an adjustment for the iacv. I deleted it by simply screwing a piece of sheet metal over the hole where the iacv originally sat, and I made sure to use the rubber seal that was on my iacv so that my patch didn't leak. Then I just looped the coolant hoses that went to the iacv together. At the time I had a bad water pump leak I was experiencing all sorts of idle issues and that's why I deleted it to begin with. I was running straight water in my coolant system and it froze over a few times, good ol cold NC mornings and I was afraid I may have broken my iacv. However, upon inspection of my iacv now it seems to function properly, I mean it spins by hand freely and it closes off as it should when I try to blow through it. So my question now is should I just clean my iacv and replace it to try and solve my 1500 rpm surge issue, or should I go buy a new iacv all together? I have replaced my water pump and timing belt now and I am running antifreeze in my coolant system. I know I will have to re-bleed the coolant system of air when I replace my iacv I just don't want to waste the time of putting my original iacv back on of there is a possiblity of it being broken in a way that I can't tell by physically inspecting it. Thanks for all the help, guys.

Joey Mitchell

Also, please don't rag on my shitty carpet. Lol

JRCivic1

An IACV would have an electrical coil inside of it so that the ECU can control the rate of air flow that bypasses the T/B. Does the device that you have pictured have some port for an electrical connection ??? If not, it would be considered a mechanical FITV. The way that these work is there is a simple air leak when the water temperature is cool... once warmed up, the wax bowl inside softens and allows the piston inside to seal thus cutting off the air leak.

This doesn't look like an IACV from a '98 D16Y7... is it damaged or is some part missing ??? There really should be a 3-wire electrical port.

Joey Mitchell

If you were looking at the right hand side of the iacv in the first (top) picture I posted you will see a brass "****" on the side of the valve. That is where the electrical coil bolts over the iacv. I just left it connected to the car, really for no reason just so I don't lose it. Lol. But yes it's definitely an iacv, and that is the missing part you described. My apologies for lack of pictures, it's just been too cold outside. I'm probably going to reinstall my iacv today and hope for the best.

mk378

Yes put it all back together.

You don't necessarily have to hook up the coolant lines though. They don't do anything except in very cold weather.

93hondacivic91

Check your tps that has a lot to do with idle not iacv or whatever you call it

Joey Mitchell

Ok, so I put it all back together, minus the coolant lines for now just to see what happened. At first it idle surged as the iacv was stuck wide open, so I unplugged it while the car was running and plugged it back in and boom, the car started running as should. I then used my obd reader and cleared the code it has been throwing for iacv since I deleted it months back. I got excited for a moment and was about to call it a fix, but my excitement was short-lived when the car randomly idled up to about 2500 rpm a few minutes after clearing the code and started the infamous idle surge once again. Everytime I unplug the iacv and plug it back in the car starts to run and idle properly as it should for a few minutes then boom, back to idle surging. I do not have a multi tester to test the voltage that my ecu is running to my iacv, so should I just assume my iacv is bad??? I mean, it did freeze over several times while the iacv was on the car, with nothing more than water in the coolant system... But when I inspect my iacv everything seems to function properly. It spins freely and stops in the spots it should. However I will say that putting my iacv back on did solve the 1500-1600 rpm issue which I originally set out to resolve, but I can't deal with this terrible idle surge and I'd like to not have a cel. Thoughts??? Again, thanks everyone for your patience and input.

93hondacivic91

TPS brotha

Joey Mitchell

Already replaced tps just a few days ago. Only code I'm throwing is iacv.

93hondacivic91

First off explain what you mean by surging. Second off to remove the cel all u got to do is remove the ecu fuse under your hood for a few minutes and its gone. Ever time i go over 6500 rpm my cel goes so i just remove the ecu fuse under hood and wam bam its gone. Also my cel was on due to a high idle idk if thats what your dealing with. Let me know ☺

tony_2018

that specific iacv is calibrated, I dont THINK you were suppose to separate them.

Joey Mitchell

On idle the car bounces between like 500-1000 rpm constantly. May not be exactly those rpms but you get the basic idea. I guess you could say it's idle bucking. But soon as I give it has it clears right up. It's either a faulty iacv or my ecu is spazzing out lol.
what exactly do you mean? I wasn't supposed to separate the iacv from the coil part?

93hondacivic91

Its just idling bro give or take thats a constant idle but if you got a cel then theres something wrong get the code and fix it asap try not to drive too irratic if you know what i mean

Joey Mitchell

Nah dude it's a bad idle surge. Plus throwing a code for iacv. It's a very common issue among the d series I just don't know if my iacv is bad or what the deal is.

93hondacivic91

So we might have the same issue, mine surges but i aint trippin about that, my main concern is the cel. So have u replaced the iacv?

DumpdEJ6

You mentioned you replaced the TPS, but you don't have a multimeter. TPS needs to be calibrated using a voltmeter, 0.5v closed and 5.0v at WOT if I recall correctly.