strider380

My 96 civic EX (i put a 99 motor in it) hesitates on acceleration. or anytime that I hit the gas under 3000 rpm. I have to drive it like there's an egg under the gas pedal in order to keep it from hesitating.

There are no CEL's. I had a knock sensor code and a oxygen sensor code. I fixed both of them. The hesitation was really bad with those codes and progressivly got better as I fixed them. But it still bogs and hesitates when I hit the gas under I'd say 2800 or 3000 rpm. And like I said, there are no CEL's currently

The motor has probably 160,000 and has a weird growl I can especially hear from the bottom side of the motor, but could just be an exhaust manifold gasket. I don't think its related. It also has an erratic idle which I don't think is related. ( i cleaned the IACV to no avail)

I am very picky about maintenance so all the plugs, cap, and everything else is up to date. I put a new timing belt in. I also timed the motor to what I think wa perfect, tho I should check it again. Reason for this was I had to use the 96 distributor.

One thing I am wondering is fuel injectors. These injectors have 160,000 miles on them. Should I take them out and bring them to a shop to be cleaned? I don't know what else it can be. Any ideas? Distributor worn out?

captn38

Pretty much same problem here on a 93 OEM DelSol Si, ( started at about 175K miles, currently at 236K) some of my low end hesitation went away when I found I had a badly stretched timing belt ( with only 60k on it ) and replaced that, but alas still have the hesitation just as you are stating ease into it no problem, punch it and it hesitates until higher rpm is reached, and also erratic idle as well, think I have checked or replaced dang near everything else, frustrating.

Sturmmann

iTrader: (3)

Seems like a spark issue. Have you tried changing ICM (Ignitor Control Module) in the distributor? How about ignition coil in the distributor?

If it is not spark, then fuel. Fuel filter, pump, injectors, maybe even ECU. But I do not think it is that drastic. Try swapping spark components with someone first.

strider380

Could it be in need of a valve adjustment? what mileage do you typically need to adjust valves at? and what mileage do you need to clean fuel injectors? I mean I run fuel injector cleaner through it occasionally but I think everyone knows that stuff dosn't do anything. would they last 160, 000?

strider380

any ideas on if i might need a valve adjustment and/or my fuel injectors cleaned? I put a stethoscope on my valve cover and it sounds smooth as silk. dn't know it that means anything

Blacknight117

iTrader: (1)

This I know won`t help but, my `95 EX has well over 250k on it and the injectors have never been changed. You could get your injectors cleaned professionally, it won`t hurt. As for the valve adjustment, I have not done it to mine yet, but again it wouldn`t hurt to get it done.

strider380

hmmm....i don't know what it could be then

captn38

In my case ICM and coil was changed a while back, but I double checked and tested them, even pulled the ICM and run it into town for a more formal diagnostic and it all checked good. I certainly do not want to fall into a ( start replacing stuff and hope I eventually fix the problem) I have read a few places that suggest Honda ignition has very critical voltage needs at low end and idle. I still have to replace my plug wires OEM and have 236k on them, fuel filter was just changed, I try to follow Honda's maintenance schedule on valve check and adjustments, although I feel every 15k is a bit excessive and I admit I have skipped a few, but they were recently checked. Fuel injectors is an area I have only checked by stethoscope they click nice but I have wondered if I might have a weak one but it is my understanding fuel pressure remains constant thru out rpm range. I tend to agree my issue is ignition/timing related as my issue is only at idle or low speed under a load, so I am curious as I do not know, what key sensor or sensors are responsible for letting the ecu know that timing advance is needed and doing the same job the old vacuum and mechanical advance systems did on older vehicles, I have been over my manuals many time yet cannot seem to find a clear answer to this.

strider380

I changed the injectors out with some that has less miles on them. Actually the tips were slightly different (96 vs 99) but they went in and worked fine. Absolutly no difference in my hesitation problem, so I am pretty sure its not the injectors. I did notice that my car starts hesitating a few minutes after its reached operating temp. It drives great when the engine is cold. I am an old muscle car kinda guy. this would normally tell me its either the spark plugs or ignition coil in any of my older cars. maybe I should throw in some better plugs? Anyone know if I can swap parts from my 99 dizzy into my 96 dizzy?

ReDHaTcHyGuy

Just use the recomended NGK v power plugs, theyre really the best u can get for a Honda.. All those expensive gimmick plugs don't really make a difference for us

strider380

Ok, so no need for iridiums? I'm under the impression that they just last longer, but not much of a performance gain if any.

flatlander

I have the same problem. Based on the diagnostics that I've done it seems like an air problem. Meaning that when I step hard on the gas pedal, the engine isn't receiving enough air to keep up. However I don't understand why. But I have noticed that when starting (which is often difficult), the car will only start if I don't hit the gas.

Things I have checked:
ECU
MAP sensor
injectors have the correct resistance
purge control solenoid valve
fuel filter has been replaced
cap, rotor, and coil (but not ignitor) have been replaced
air filter is new (not clogged)
fuel pump works (makes noise for 2 seconds when key is turned)
PCV valve is not clogged
Also, I sprayed carb cleaner through the air intake while revving the engine to try to clean out any clogging in the throttle body or manifold, but it didn't help at all.


Things I have not checked (because there is no Check Engine Light):
TDC/Crank/CYL sensor
Throttle angle sensor

Any suggestions?

motegicivic

Don't forget the 99 motor has the cold start valve the 96 does not, I am wondering you need a 99 ECU, plus I am not sure if there is seperate harness for the cold start valve or not.

scribble912

Check to make sure your FIACV isnt causing a direct vacuum leaking, causing your fuel cell to not read correct. I had this same issue where it would hesitate between 2500 to 3000rpms while under a slight acceleration. fuel trims were also elevated which points towards vacuum leak. you might have to let your long term fuel trim compensate before all is corrected or reset them. this valve should only draw vacuum from the intake below 149deg F. if your vehicle is at Op. temp and you pull the hose from the intake or air cleaner side and it has vacuum on it when you plug it with your finger this is your problem. I just plugged mine with a vacuum cap at the valve and all is well. This is just my winter beater though. 99 civic ex "stock"

MO Problems

I had the same problem last month. Ran perfect above 3k but getting on the gas under 3k seemed like it was missing. I started with the cheapest route and replaced the spark plugs. Ran like a champ afterwards!

captn38

I thought I had responded here stating my solution and correction for this same problem as originally posted, after checking what I felt all I could do, I started wondering about the crank position/TDC sensor which is integrated in the distributor. I took a chance and not wanting to pay new price I bought a complete distributor assembly off a low mileage 93 delsol wreck out of a salvage yard, installed this distributor on my car, ran fine, did the fine tuning on timing and this thing ran like new, no more hesitation or stumble, that was the problem obviously.