KaBlookie

So I’ve been having this weird intermittent hesitating/sputtering issue, and I’m completely stumped at this point. I searched and read through a bunch of threads here and numerous others on other forums, and those threads either didn’t pertain to my particular situation, or I already tried what people suggested.

Here's what I've checked:

- MAP sensor circuit
- MAP sensor resistance (on the sensor, compared to another one I had lying around)
- MAP sensor voltage at ECU
- TPS circuit
- TPS resistance (on the sensor)
- IACV circuit
- everything in the distributor (ignition coil, ICM, etc.)
- distributor cap and rotor
- checked for grounded out connections (tested for conductivity between a bunch of sensor wires and chassis ground)
- spark plug wires (quality of connection and resistance)
- spark plug torque
- spark plugs (checked gap and inspected for fouling)
- resistance across each injector
- now running a used O2 sensor...better than before...but it still hesitates sometimes
- no noticeable vacuum leaks
- all grounds
- tried out a GSR ECU
- visually inspected cat converter
- air filter, oil, oil filter, fuel filter, and clutch are all fine
...and I believe that’s it

What I haven't checked:

- TPS and MAP sensors when the key is in the "on" position and connector is attached
- IACV operation (car idles totally normally during warm-up though, so I’d assume it’s working fine)

What I've found:

- If, when I’m driving, I take each gear to like 3500 or 4000rpm or so, it doesn’t hesitate...it mostly does it when I drive the way I always did and keep the RPMs below 3000, mostly driving in the 2500rpm range.
- When in neutral, it revs 100% normally and is fully responsive
- It starts and idles perfectly fine to begin with, then from time to time, when I come to a stop after driving, the idle will drop to 200-300rpm and if it doesn’t catch itself and pop back up to normal idle on its own, a small blip of the gas pedal does
- A couple of times, I’ve been even with the throttle while it was hesitating, and the hesitating would just stop like a switch and the car would start driving normally...
- With both ECUs, I checked the voltage at the connector to the MAP sensor and from each of the side contacts (one's power, one's signal) to the center contact (ground), I got 5-volts for one (normal) and 3.6-volts for the other. I was a bit worried about this until it happened with both ECUs...so I don't think this is the problem
- I replaced the MAP sensor with the one from my old engine (which worked fine), and nothing changed
- It almost never happens after the car has been up to full operating temperature for 5 or 10 minutes

Any suggestions or tips? I know this is a lot but I just wanted to cover all the bases so people weren’t asking or suggesting things I’ve already done. If I remember anything I did and didn’t post here, I’ll update it.


Modified by KaBlookie at 4:56 AM 9/11/2008

victorandolph

valve adjustment

KaBlookie

Do you mean valve lash adjustment? If so, then I really don't see how that would remotely cause intermittent hesitation issues...please elaborate. The engine sounds perfect while it's idling...no abnormal noises or anything.

SPECR

Clogged injectors? Was the engine recently installed after sitting for awhile? I am assuming it was since it was a JDM motor.

KaBlookie

The engine's been in my car for almost a year and like 13k miles now. When I first installed it, it had been sitting for like a month or two (bought it off a guy on here) and I did run a fuel system cleaner through it, but that wouldn't be the problem now.

Also, I'm not sure if clogged injectors would cause an intermittent issue. I'm also still getting really good gas mileage (27-30mpg more city than highway...in the heat...)

CW-ITR

iTrader: (11)

Any loss coolant issues?
Sticking valve(s)
The whoe issue happens on the same tank of gas?

KaBlookie

Coolant level is steady, I don't believe any of my valves are sticking, and I'm on my second tank of gas since this issue has started (different stations).

CW-ITR

iTrader: (11)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by KaBlookie &raquo;</TD></TR><TR><TD CLASS="quote">Coolant level is steady, I don't believe any of my valves are sticking, and I'm on my second tank of gas since this issue has started (different stations).</TD></TR></TABLE>These two ruled out my suspicion about bad gas or coolant leak. However, double check your valves.

BLacK FirE

iTrader: (2)

I had this problem at one point. Cap and rotor had to be replaced. When you said you checked this already, just visually or did you swap in a new one?

KaBlookie

CW-ITR, aside from not hearing anything abnormal, what can I do to "check my valves?"

I visually inspected the cap and rotor...I technically could swap them out for another cap/rotor I have but it looks to be in the same (or similar) condition, and it was on an engine that ran perfectly fine.

Was your problem intermittent and mostly only occurring below 3k-3.5k rpm?

BLacK FirE

iTrader: (2)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by KaBlookie &raquo;</TD></TR><TR><TD CLASS="quote">

Was your problem intermittent and mostly only occurring below 3k-3.5k rpm?</TD></TR></TABLE>

Yep everything you described was exactly what I was going through. Wierd thing to was it didn't do it if I went full throttle. Eventually it started to misfire at idle, checked the cap and rotor and it smelt of burnt plastic.

KaBlookie

Weird. I swear if the only issue is the cap and rotor, I'll be glad as hell it's something cheap, but I'll be a little pissed cause this has really confused me and other people (this same discussion on another forum is almost three full pages long now) for a while now.

Does anyone know if there's any functional difference between the LS, GSR, and ITR ICMs? I know they have different part numbers, but is there anything more than that? I'm asking for two reasons...the distributor I'm using is from a GSR, but it's been perfectly fine for all this time now. Also, I have my distributor from my old engine (B18B), so if they're actually the same I could just swap it out to see if that's the issue.

MPT23

I had the exact same issue with my jdm b18c swap. I replaced the TPS sensor and i havent had a problem since. To check it back probe the center wire on the tps with a pin or paper clip and check voltage with the key in the on position. Should be around .45 - .50 and 4.45 or higher at WOT.

KingKnight

Maybe take it to a shop.

KaBlookie

KingKnight, I don't pay people to work on my car...even with something like this, I couldn't justify spending money to have someone else try to fix it.

MPT23, I'll try that. I've wanted to do that, but the sensor connectors are sealed from the back...but I hadn't thought of using a paper clip...thanks!

jdmscg

iTrader: (3)

Do u have access to another b18c dizzy? If so try swapping them to see if it goes away...Sounds like dizzy failure to me...GL

CubanoRockr

probably a stupid question but have you tried to fill up on good quality gas (chevron) and reset the ecu? have you checked the timing of both the timing belt and the dizzy (just to rule that out) is the cold idle good? (fast idle thermo valve) as in the small plate with two bolts - inside you have a cone (metal) and 2 slotted (plastic) pieces on either side that have to be tightened, if not funny issues do come out of it

and what kind of ecu are you running? to do a temp substitute by swapping a b16 computer technically not enough fuel but the right ignition maps to match the intake manifolds (gsr will require different maps for the dual runner)

KaBlookie

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by CubanoRockr &raquo;</TD></TR><TR><TD CLASS="quote">probably a stupid question but have you tried to fill up on good quality gas (chevron) and reset the ecu? have you checked the timing of both the timing belt and the dizzy (just to rule that out) is the cold idle good? (fast idle thermo valve) as in the small plate with two bolts - inside you have a cone (metal) and 2 slotted (plastic) pieces on either side that have to be tightened, if not funny issues do come out of it

and what kind of ecu are you running? to do a temp substitute by swapping a b16 computer technically not enough fuel but the right ignition maps to match the intake manifolds (gsr will require different maps for the dual runner)</TD></TR></TABLE>

- This has been happening for a couple of months now, and I've had numerous different brands of gas in with no difference in between
- I did try to reset the ECU. Nothing happened.
- I have not checked any timing, but if it was a timing issue of any kind it wouldn't be an intermittent problem...especially if it was a timing belt issue.
- Cold idle is just as it should be. When this issue comes up, it only happens under load.
- This engine doesn't have an FITV...it's a 97. I did check the IACV though, as stated in my OP.
- I'm running a JDM ITR ECU, exact same OBD generation as the engine.
- I have swapped in a GSR ECU and there was no change in the frequency or severity of the issue.

MiraiZ

What octane are you using?

bad1_s2k

I think I'm having this issue now. But My engine harness is all choped up so I'm going to try and take care of that first and see if the problem goes away

eg_type_r93

change your fuel filter and run a injector cleaner throught your gas tank and spray the throttle body out with injector cleaner.

Girlzcn2

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by KaBlookie &raquo;</TD></TR><TR><TD CLASS="quote">

Also, I'm not sure if clogged injectors would cause an intermittent issue. I'm also still getting really good gas mileage (27-30mpg more city than highway...in the heat...)</TD></TR></TABLE>


clogged or bad injectors could <U>definitly</U> cause this issue. i have had injectors go bad and spark plug wires go bad. it doesnt have to be all of them but if you have a problem with even just one of them, your car will hesitate and progressivly get worse.

process of elimination....easiest first, dont check but change the plugs wires and injectors

KaBlookie

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by MiraiZ &raquo;</TD></TR><TR><TD CLASS="quote">What octane are you using?</TD></TR></TABLE>

93 octane all the time.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by eg_type_r93 &raquo;</TD></TR><TR><TD CLASS="quote">change your fuel filter and run a injector cleaner throught your gas tank and spray the throttle body out with injector cleaner. </TD></TR></TABLE>

Fuel filter was done late winter and I have run injector cleaner through it.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Girlzcn2 &raquo;</TD></TR><TR><TD CLASS="quote">
clogged or bad injectors could <U>definitly</U> cause this issue. i have had injectors go bad and spark plug wires go bad. it doesnt have to be all of them but if you have a problem with even just one of them, your car will hesitate and progressivly get worse.

process of elimination....easiest first, dont check but change the plugs wires and injectors</TD></TR></TABLE>

I don't doubt that a clogged injector could cause an issue, what I'm saying is that it's not likely it'll cause an intermittent issue. If an injector is clogged, it's clogged and will cause issues...if it becomes unclogged, it's unclogged and will no longer have issues related to that. A clogged injector isn't an intermittent issue, it's either there or it's not.

Also, it hasn't been getting worse...it happens under certain circumstances and not under others. As stated earlier, I replaced my o2 sensor with a different used one and the issue is less prevalent, but it still happens. I also did replace my spark plug wires with some I had lying around and nothing changed.

I do have a set of OBD2 injectors lying around, so maybe I'll throw those in once I get a chance...just for kicks.

MiraiZ

Just a note, 93 octane is regular in Japan. The minimum high octane rating here is 96 (RON) with most carriers providing 100 (RON). Not sure if this is your problem per se, but I was told that high octane gas is essencial on the JDM ITR.

KaBlookie

I hear ya on the octane thing...correct me if I'm wrong, but their scale is different though, so chemically their 93 is similar to our 87...kinda...

Also, this issue has only been happening recently, after being in my car for around a year and ~13k miles.

I also don't think it would be totally out of line to blame the slightly increased ethanol content in gas over the summer...i f*king hate that ethanol is in virtually every gas pump...it has no practical, realistic benefits unless you're running E85 and are tuned for it. But anyway, I digress...