12 replies to this topic

[mn85crx]

I have a D16A1 blacktop swapped into a 85 CRX Si. Everything is working great, the swap went good. I have one issue though. When I start the car it starts up great and sounds really good at high idle. As the car warms up and the rpms drop to around 800 rpms it begins to sputter a little and the idle fluctuates rpms between 600-800 and keeps dipping and coming back. This is with nothing electrical turned on to cause any extra load on the engine. This problem also show up while driving. It is only when taking off from a stop. The car sputters and then something clicks and then it runs like a champ and pulls hard and feels strong. It chugs and sputters till about 2500-2800 rpms then this click happens and it drives great. I am having a hell of a time figuring out what is causing this. This is the last real issue with the CRX to sort out, everything else about the car is great, I really want o to get out there and see what this blacktop can do. I only have 300 miles on it since the rebuild and this issue does not make it enjoyable to drive to break in the engine and then start really driving her.

I am thinking it is something electrical, either with the ECU or with a sensor on the engine. I am not throwing any CELs and the only thing I don't have hooked up is the VSS, would this cause an issue like this because the ECU doesn't know how fast the car is going? I thought I heard that the VSS signal is used to alter the fuel being injected, is this true? I have also heard that you can drive the car without the VSS and it shouldn't affect anything, and only throw a CEL on a long decel.

I am getting very discouraged with this issue and any insight anyone has is much appreciated. I cant think of what else it could be. The fuel filter in the engine bay is new, the plugs are new, the cap and rotor is new. The plug wires aren't new but I checked their resistance and they all came back good. I tried searching the forums here and I haven't found anyone that is/has had this issue, help!

Thanks.
Scott

[kaymo]

even though the rotor button is new, that does not mean you should not check it. i had a brand new rotor button rotate on the shaft. im not saying this is your problem, but you should still check under the cap to see what you can see. i hope you find your problem bud!

[anjin]

If its a blacktop then it has a electronic engine speed control on the back of the throttle body. This is known to get clogged with recirculated stuff from the valve cover hose, and cause problems with idle. Clean it with carb cleaner. That sounds like it could be part of the problem.

The click part could be the pcb valve sticking shut and then opening when the pressure differential gets high enough. Clean or replace it, after working out how to get to it. Its below the intake manifold.

If its one or both of these then they are easy enough to do.

[mn85crx]

anjin, thanks for the advice. I am a little confused about the sensor you are talking about. On the back of the throttle body I have the TPS sensor. On the back of the intake manifold there is the EACV, is this the sensor you are talking about cleaning? Also, on the front of the throttle body there is a diaphragm dashpot assembly with a hose from the intake manifold, is this the sensor to clean?

I have tried searching for the electronic engine speed control and have not come up with a sensor with that specific name. I think I will try to clean both of these and see what happens, I wouldn't think it would hurt anything.

Thanks,
Scott

[mn85crx]

I have a theory and I want to run it by you guys. I cleaned out both the sensors and it seems to help for a bit and then the idle came back again and the taking off from a stop issue cam back again too.

I noticed if I keep the revs up just a little off idle then when I take off from a stop it doesn't have the weird sputtering issue. I know last year after I completed the swap I tried messing around with the idle and I think I screwed it up and it is too low now. I am thinking this may be why the idel dips so low that it might die then it bounces up to stay running and this is the fluctuation I get. I think if I can turn my idle up, just a little bit it will run and drive much better. Does this make sense at all or am I grasping at straws?

I remember a while back seeing a post that had the procedure in it for adjusting the idle on a blacktop D16A1. I know there are a few things you have to do, and I don't think the crappy Chilton manual has all the correct steps in it. What is the procedure for a blacktop, or does anyone remember what thread that was in? I searched and came up with nothing, I also thought I marked that thread but I ca find where the marked threads are in my profile.

Thanks,
Scott

[Rampage]

After swapping in a blacktop I had an idling issue where it would go lower, lower, and lower still until the computer kicked the idle up to 1250, and slowly brought it back down to about 750...

The most likely reason for this was build-up of carbon on the EACV, to the point that when the computer was trying to hold a low idle, the passage was blocked off enough to confuse the computer (thinking it would get more air than it was from buildup) This is probably the case as well for my idle passageway past the throttle body.

I unscrewed the idle speed screw one turn and haven't had a problem since!

Remember, the idle speed is controlled by the computer, not the idle speed screw, all I was doing by opening the screw a bit was compensating for a partially plugged idle passageway. This way the computer didn't have to fight with the EACV as much to hold a steady idle. I hope that makes sense.

As for the sputtering, try a turn or two on the idle screw first, as well as a good cleaning of the throttle body with some carb cleaner.

Furthermore, you should have your VSS and ELD problems sorted out, but they won't really cause major power loss at low RPM as you describe...However, with a check engine light on, your engine may be running in open loop, as in no O2 regulation, so it may just be putting in a pre-determined amount of fuel in: Rich running.

Cheers,
Mark

[87civDX]

i had the same problem with my 88 civic i know that its not the same engine but it had the same problem so i called my friend who worked at honda for 10 years and he threw a timing light on it and adjusted the distributer and the problem went away he told me that the timing was set back so far that the computer was alwais changing the idle speed in order to keep it running. this could also be why it hezitates when you take off because the timing is not advancing far enough. but a sign of the timing being set back to far is really hard starting. but it is worth looking into


btw when i say the timing is set back i mean retard i just didnt want to say it because kaymo made fun of me last time

[strudel]

Scott,

Warm the engine up to operating temperature. Disconnect the 2 pin connector at the EACV. You will throw a code. Then turn the idle set screw on the TB to the correct idle, approx 750-800 RPM. Then reconnect the wiring and reset the ECU. That's how you set the idle, not the computer.

Try to have someone help you find the clicking sound. The EACV does click. You will hear it if you disconnect and reconnect it. It basically has a type of solenoid inside that the computer regulates by comparing operating temperature as it is basically an electronic choke. It slowly reduces the high idle as the engine warms up. It is also dependent on 2 other sensors as far as I can determine. The 2 pin connector on the head that senses the engine temperature for the ECU, not the 1 pin for the temp gauge in the cluster. The other is the IAT on the side of the IM next to the MC. Take them both out and clean them or replace them with another unit. It does not hurt to remove the EACV and clean it out with carb cleaner or similar and blow it dry with compressed air. All you will see in side is a plastic bellows but do try to get all the carbon out as best you can.

If you are at idle and the engine surges it is from what I described above. If it is spluttering or surging as you accelerate then I would think it is something else. After you have the idle set as described above and the car is warm drive without the EACV wired up and see what happens and if there is anything different. If not then that's not the issue. I can disconnect the EACV with a switch I rigged up and it turns it off completely and the surging stops and the car runs great. My car only occasionally surges at idle and not while driving.

Try and find out if the clicking sound is inside the car or in the engine bay. This is a stretch but if your main relay is at issue that might be the click but that is normally only a starting issue and not while driving as it controls the fuel pump.

Does this splutter happen if you just rev the engine in a stopped position? If so, stick your nose under the hood while someone else revs it for you. Or put the front on jack stands and run it in gear with the wheels off the ground. There are not many things that should make a clicking sound. It was mentioned that the PCV valve may be at issue. It may click if you have your ear to it but I wouldn't think you could hear it inside the car but then again who knows for sure. Hope that gives some insight, good or bad. JS

[mn85crx]

Alright, I finally got back to working on my CRX. I just picked up a 79 Civic CVCC Wagon so I have been focusing on getting that road ready.

So I decided to attack this problem with a though out plan and check everything one by one. I decided to check the valve timing and make sure that it was still good to go. When I rebuilt the engine I left the timing cover off and made a mark on the oil pump in place of the timing mark on the cover. I went back now and modified the timing cover to bolt on and use the stock timing mark...low and behold the timing was off by two teeth. I fixed the timing and started her up, she purred like a kitten and had no hiccups in her idle.

Then I took her out on the street, Holy S%$&, this car is fast as hell! It revs up so freely and drives like a dream. I had been driving it around with the incorrect timing and I kept thinking to myself, wow, this car isn't that fast. Little did I know how fast it was when it was running correctly.


There is still one thing, my PGM-FI light is now on and throwing a code 9, which is the Crank Angle Sensor. I checked in the manuals I have, and the resistance of this sensor should be between 650-800 ohms. I check mine and it is only at 440 ohms. I think I need to replace this sensor. My questions is can I replace this sensor alone, which is inside the dizzy, or do I have to replace the whole dizzy assembly?

Thanks for everyone's input on this issue. Had I listened to Scott's usual words of wisdom and check the basics right from the start, this problem would have been taken care of a long time ago.

Thanks,
Scott

[EuphoricBlue]

The guys at the yard will tell you that you need to replace the whole distributor. BS. You might have to splice the wires but you can replace just the pickup.

On my MR2, the guy told me it can't be done. So I went into the yard, found a celica with a different distributor that someone had picked at. Pickups looked the same so I pulled them all and paid the man his 5 dollars. Now my MR2 no longer has a code and I have 2 spares. Saved my self a couple houndred dollars for a remanned dizzy.


The real question is, will the yard allow you to grab just the pickup, since the distrubutor will be scrap without them.

[strudel]

Scott,

Congrats on finally getting this resolved. If you wouldn't have checked the resistance of the sensor I would have suggested one cam to be off one tooth as that happened to me after changing a timing belt. Enjoy driving it, finally! JS

[EuphoricBlue]

Scott,

Congrats on finally getting this resolved. If you wouldn't have checked the resistance of the sensor I would have suggested one cam to be off one tooth as that happened to me after changing a timing belt. Enjoy driving it, finally! JS

His cam timing WAS off, two teeth in fact

[mn85crx]

I forgot to mention one thing. When the timing was off two teeth there was no code 9, weird.

Now that the timing is spot on and it is throwing a code 9 that leads me to believe the sensor is messed up and needs to be replaced. I will check the timing one more time but I am pretty sure it is spot on.

Scott