Hesitation I can't get ride of ... help!

Resurecting this thread to pose a follow-up question.

I tried this trouble-shooting proceedure with my '92. Should it hold for the pre OBDII cars as well? I'm fairly certain mine only has 2 O2 sensors, one per bank. The MIL throws an O2 sensor code, and the TCS light is on (although I'm pretty sure that is related to a dead speed sensor because the speedo is also non-functional).

I disconnected the sensors, and while the car was cold, it seemed to aleviate the hesistation, but that might have just been the car running in "cold" mode, once it warmed up, it resumed balking when anything more than half throttle was applied at ~2-2.5k rpm. So once warm, it runs the same with the sensors disconnected as it did with them connected. Of course, logic suggests, that being the case, the sensor(s) must be bad, but I figured a more experienced second opinion couldn't hurt. (I've had the car 4 days :biggrin: ).

thanks!
 
If I remember correctly, a bad O2 sensor will also throw the TCS light.

TitaniumVTEC has gone through a multitude of O2 sensors so he could probably help you there, but I think that's exactly what you have given the symptoms you've stated.
 
All clues point that direction right now. Since I'm so new to the car, I just want to make sure though.

If I had bought another MR2, I would have driven into the first parts store I came across after I left the sellers house and probably fixed everything wrong with it in about 2 hours in the parking lot before driving the rest of the way home.

The speedo could be unrelated since the dash lights are also occasionally flaky (they tend to flicker if I hit a harsh bump/hole...which, I discovered, is unaviodable in NY/NJ. It hasn't done it since I've been back on properly paved roads.) . I might just have a bad connection behind the cluster that could explain the speedo.
 
the dead speed sensor will turn on check engine light and traction control light and will make the car run in limp mode.
 
You may have to define "limp mode" for me. It doesn't feel like limp mode, but I have no point of reference for an NA1. The only other NSXs that I've driven and/or ridden in have all been NA2. "limp mode" on my MR2 was just an issue of the ECU retarding the boost and/or cutting fuel.

Either way, i have all three items (2 O2 sensors & 1 speed sensor) in hand to install Sat. morning, so hopefully somewhere in there, I'll take care of it :smile:
 
well if it doesn't work then if u read the entire thread, it could be the ignition switch--cause I had the hesitation issues and the dash light thing before it went totally bad and started to stall. When it wouldn't start, turning the ignition switch caused the starter to engage but the car wouldn't start but this was at the tail end of the problem...
 
Update:

Replaced both O2 sensors (those things are a PITA...I need an O2 sensor wrench badly). Replaced the speed sensor (speedo works again).

I reset the ECU and I'm down to one code: 6, the coolant temp sensor.

The CEL & TCS light are both still on.

The car still runs like crap below 3200 rpm. Does the coolant temp sensor talk to the ECU with respect to fuel mix/idle speed?
 
Ok, sorry to post so many times on a topic that may have already run it's course.

I have cleared all engine codes now by replacing O2 sensors, speed sensor, and coolant temp sensor.

Good news: no new CEL codes, Car no longer running with curtailed rev limiter.

Bad news: Car still sounds like its down a cylinder at idle, and hesistates between 2000 & 3200 rpm.

I do not know what the prev. owner had done with regards to plug/injectors. I plan to check those items next as well as EGR. I've also heard the ignition switch mentioned, but I have not had any other symptoms of that failure.

Are there any other things I should check first?
 
What is your coolant level in the bottle?

Is it loosing coolant?

Regards,
LarryB
 
R13 said:
Bad news: Car still sounds like its down a cylinder at idle, and hesistates between 2000 & 3200 rpm.
Click to expand...

Did you check the ignition coils?

Sidenote: Checking Ohms (1.3) is only part of the check. Also check for corrosion. A coil going bad usually shows its symptoms at idle first, then start to fire as the rpm's rise.
 
Cant believe no one has said to replace the main relay... its cheap and easy to replace.
 
Larry Bastanza said:
What is your coolant level in the bottle?

Is it loosing coolant?

Regards,
LarryB
Click to expand...

The coolant level has been at spec since I got the car. I lost some while changing the coolant temp sensor, but it was replaced up to the desired level and I have experienced no heat issues since. I can also confirm, to the extent to which I can measure, that the car isn't losing coolant.

(I wonder if you know this car? Up until now, it had spend its entire life in White Plains)

goldNSX said:
Did you check the ignition coils?

Sidenote: Checking Ohms (1.3) is only part of the check. Also check for corrosion. A coil going bad usually shows its symptoms at idle first, then start to fire as the rpm's rise.
Click to expand...

I have replacement spark plugs which will be going in this weekend (or before if I get some time). I will be inspecting and checking the coils at that time.

enkrypt3d said:
Cant believe no one has said to replace the main relay... its cheap and easy to replace.
Click to expand...

I haven't looked at or touched the main relay (though I will since you bring it up :biggrin:. In the interest of full disclosure, I also have issues with the gauge-pod lighting not working or working intermittantly. The gauges themselves work, as well as all of the idiot/notification lights, and the console (A/C & Radio) lights work all the time. Could the two issues be related??

Thanks for the help!
 
Last edited:
R13 said:
The coolant level has been at spec since I got the car. I lost some while changing the coolant temp sensor, but it was replaced up to the desired level and I have experienced no heat issues since. I can also confirm, to the extent to which I can measure, that the car isn't losing coolant.

(I wonder if you know this car? Up until now, it had spend its entire life in White Plains)


Thanks for the help!
Click to expand...

OK, that is good news. In prior experiences I have seen the "6" code for the temp sensor, but it is really due to low coolant in the cylinder head. The results for that is bad head gaskets or some other coolant leak.

Your comments would lead me to continue to check for electrical issues (spark plugs, coils, etc) as suggested. Try to isolate the misfiring cylinder then you can find the exact cause.

Hard to say if I know the car, I only know it is a 1992!!!!:). Give me a little more info about the car: color, previous owner name, mileage, etc. I see a lot of 1992's;).

Regards,
LarryB
 
I figured out what was causing a slight/heavy hesitation on my 92 nsx.

after changing out sparkplugs and ending up with OEM plugs, my mechanic and I still pussled about why on the first drive of the day you could even feel the cars hesitation we deducted it was because the ECU was "seeing" a cold car, thus causing it to perfome normaly and when the car reached operating temperature it would start hestitating again; we unplugged the ecu's water temp sensor. this caused 2 things, NO FANS were running (please pay attention to your temp gauge or you will fry your engine) and 2 no more hestitation. problem solved. for the most part as now it moved from a very wide range of the rpm band to very near where the fuel pump switches from low to hi. I'm replacing my fuel pump just for teh sake of it, it's 16yo!

david
 
djimenez said:
I figured out what was causing a slight/heavy hesitation on my 92 nsx.
we unplugged the ecu's water temp sensor. this caused 2 things, NO FANS were running (please pay attention to your temp gauge or you will fry your engine)david
Click to expand...

I don't know what you unpluged but the ECU does not control the cooling fans and the fan control system does not interface with the ECU.
 
As an update, I'm going to tentatively call my problem (well the one addressed in this thread anyway) solved.

So, in order of what solved what:

O2 sensors: cured inconsistent idle speed, & cleared CEL

Speed sensor: re-enabled speedo, cleared CEL

Coolant temp sensor: Removed "limp mode" rev limiter, cured fast idle, cleared CEL

**Spark Plugs: eliminated misfire in warm-idle, and hesitation when accelerating from low RPM.

The coils all checked out, although the covers that go over the coils were missing their gaskets, and I can't imagine water would do any of those components much good. I'll be replacing those at my next opportunity.

Thanks for the responses folks. This, along with replacing the oil-pan gasket (which I did this morning) takes care of the last significant mechanical issue with the drivetrain.

The car is a helluva lot more fun to drive when it works right :biggrin:
 
BrianK,

By any chance do you have a picture of the actual sensor (#23) on the car? i cant seem to find it, and my service manual picture is odd, it appears to be hanging from the water reservoir.

TY very much for you help,
david
 
In all of these hesitation problems: When everything else has been checked and you still have a problem, look at the basics. I had the hesitation at tach speeds of 3000 and up 3 years ago. After screwing around with the more complex probabilities, I found I had a loose baffle in one of the after market muffler/exhaust systems. I had the car running in my driveway while actuating the throttle control by hand. The sun was shining on the back of the car just right where I noticed dust coming out of one of the tail pipes. Well, it was fiber glass not dust coming from part of one of the mufflers in an expensive stainless steel system. I guess the innards weren't full stainless. Anyway, that was my problem. Once cleared/replaced, I was a happy camper.
 
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Briank said:
Here you go, the white in the lower left is the coolant bottle.


Click to expand...

That was the culprit in my case, and it's an SOB to get to. I un-mounted the coolant tank to get a little more wiggle-room, but I needed an unusually skinny deep socket to get to it. Still didn't take more than an hour or so once I found where it was. I did the same thing (pulling the gauge sender) initially because I hadn't read that other thread.
 
well, guys..... my car played a trick on me. I replaced the water temp sensor and guess what? STILL HAVE HESITATION.

I now decided to disconnect my cars TPS, check engine light came on, TCS light too. NO MORE hesitation. Did it twice and now I can reproduce and eliminate the fault.

The question is, I cannot buy it by itself what should I do?

david
 
hey while everyone is replacing their main relays.

can you guys send your old main relays to me? ill pay shipping

i need one and im sure there are one or two good ones that get thrown out wiht the bath water. :smile:
 

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