Hey guys, looking for a bit of help here. I'm have trouble troubleshooting a low RPM stutter in my car. It started with a small bock or miss at low RPMs every now and then about a month ago. Thought it intentionally just my fuel lines being dirty so I ran two full tanks of premium gas and a can of Seafoam in the first tank, and Lucas Full Fuel System Cleaner in the 2nd with no fix. So I started with the small ignition and fuel parts like fuel filter, spark plugs, dizzy cap, rotor button, and wires. After that no fix, I started moving to the more expensive stuff. I replace the ignition coil, still didn't fix my problem. So then I did fuel pressure test on my car, and found it at 32 PSI. Within spec, but I felt like it was a little low. So I went yesterday to get a fuel pump. And I was leaving the auto parts store to put the fuel pump on, the car started to have more problems. It started stuttering really bad until I got past 3k RPM, and then it goes away. So I got home and put the new fuel pump in, still with no fix. I checked the fuel pressure again, this time with 36 PSI with the vacuum hose connected to the FPR, and 42 with it off. So plenty of pressure. So I read around on a few forums, and saw that a lot of people that had my problem replaced the Ign Control Mod. So I went back to my auto parts store, and bought one of those and installed it. Still didn't fix my problem. Now I'm stumped and don't know where to turn. It stutters until 3k, unless I'm easy on the throttle under accleration, but once I get passed 3k, it goes away. And it also feels like it misses every now and then when idling. Anyone got any ideas?

 

Any check engine light? That sounds more like a bad sensor

 

Nope, no CEL. I unplugged the IACV just to make sure. Did that, check engine light came on. Cut it off, plugged it back in, reset the ECU, and turned it back, CEL went away.

 

MAP sensor?

 

Check your timing. If that goes well, test your Throttle Position Sensor.

 

Kind of a dumb question. But if the timing was off, wouldn't that make the car run like this at all times, and not just after it warms up? It feels like it's something electrical that's just sending out the right reading.

 

Check your ignition timing, if good then compression test. You should have done them first it's, free to rent the tools and you know exactly what the state of the engine is.

 

x2

 

Took y'alls advice and had my techs at work help with compression test and timing light. Compression is showing close to 181 across all 4 cylinders. I think cyl 2 was 182. Timing light, cold run it was dead on the money from idle all the way to 4K, didn't want to take it any higher. Drove to get up to temp, and did the compression test and the put it back on the light. It was very sporadic until about 3k and cleaned up just likes been doing while driving. Where do I go from here?

 

So compression test when at normal operating temperature is good? And you said the ignition timing is jumping around before 3k, so even at idle @normal operating temp it is sporadic?

 

Has the car always been in good mechanical condition, no leaks, not overheated, timing belt changed and proper oil change intervals? Before I know what your answers are to my last post it seems like it's definitely pointing you to and ignition/timing issue. I've only ever seen ignition timing jumping when:
A. Distributor is not tightened down allowing it to move
B. Crank pulley was put on and it either was missing the keyway or the keyway slot was damaged and allows it to shift back and forth.
C. Spark plug/s is fouled and not burning the fuel every rotation, causing the fuel to build and then boom a huge explosion and it will jump around.

 

Could this mean that one of the sensors in the distributor is failing?

 

No if an internal sensor was failing it would throw a cel they are monitored by the obd system. Any fault in one of the sensors initially would be stored as a pending code and after a certain amount of key/drive cycles if it is still present it will set a code.

 

Thanks. That was my only idea on this problem, sorry!

 

The guy that owned the car before, took really good care of it, like I have for the past 4 years. I've always changed the oil every 3-4K miles with nothing but Honda filters and Castrol or Mobil 1 high mileage oil, 5w30. The car has nearly 260,000 miles on it, original motor. I had the water pump leak, so I changed everything, timing belt, tensioner, ect. After that, it ran the best it had since I got it. ( and I never let it run hot, it got just barley over half temp when I caught it).

But answer more of your questions, yes it's sporadic under 3k when accelerating. If you keep at steady at any RPM it runs fine.

 

The water pump and everything was replaced in March of this year.

 

How do the new spark plugs look now that it's been run a little bit?

Even though compression was good at 180 PSI, it doesn't mean the rings are good.

My last motor, the oil was sealing #4 piston to give 200 PSI max compression.

It is a higher mileage motor. If it's experiencing enough blow by it can idle peculiarly.

A leak down test will indicate a scenario like this.

 

So you say sporadic under 3k when accelerating, what about idle speed is it constant?
You said the water pump was changed, is the crank pulley tight as I mentioned earlier if the keyway is loose or gouged it can cause the issue of the pulley jumping. Also are any of your plugs fouled, or cel on?

 

The crank pulley seems to be pretty tight, no movement. Idle is consistent, stays around 750 rpm, little higher when it's not up to running temp. It will drop down to 600 every once in a while, but it's done that since I've owned it. Spark plugs look clean actually. There is a little bit of black close to the threads and what have not. But the spark area is clean as a whistle on all 4. I will say that it did get a little better with changing the ign control module. It's not bucking near as much, but it's still doing it. If I'm really easy on the throttle while accelerating, it doesn't buck or anything. But if I got let's say 1/4 or 1/3 or above throttle it will jerk and miss like crazy until I get pass 3k. And like I said before, it doesn't do any of this until after the car warms up and the ECU takes over.

 

I included a picture of possible faults for your issue.
So we've covered almost every thing that could cause it, I really feel like something is being overlooked on your end perhaps. It hard for me to help you 100% though because I don't have the car in front of me and am just going based off what you are saying. I would recommend if you feel that there is nothing wrong with the engine but you are still having the issue to get it diagnosed by a reputable repair shop. Let us know the outcome regarding what happens.

 

Check the vacuum lines for tiny cracks or holes.

 

Thank you guys for those. I'm going to try something out today. My friend has a 92 hatch with the same motor. So he's going to come over and we are going to try to swap a few different parts. I'm going to try MAP, IACV, O2, and if non of those, his ECU if it comes down to it.

 

Well after the diagnosing and ruling things out by changing parts with my friend, I finally found the culprit. My problem ended up being the Throttle Position Sensor. I would have updated sooner, but in the process of taking my TPS off, the bolt holes where the TPS bolts into, broke away from my throttle body. As I was trying to remove the bottom break-away bolt, the TPS shattered around the bolt and a piece of the throttle body literally broke off. So I had to hunt down a new one before I could install the new TPS sensor. Luckily, my local Pull-A-Part had 95 Civic with a D16Z6 that just came in the day before. So I robbed the whole intake manifold and everything for less the $80. I got the intake mani just because whoever changed the AICV last time cross threaded one of the bolts. So I swapped over everything this weekend. And she's running like a champ again.

 

Glad I could point it out.

 

Good to know! Am I correct that the TPS is not available from Honda? What to do if your TPS is bad, but your throttle body is not breaking into pieces?