Random stuttering, bucking, skipping from CRX HF

[shag wagon]

Ok I am having some stupid issues with a CRX that obviously wasn't maintained like it should but I have tried to get the thing back into tip top shape but with no prevail. I am having an issue that once it gets good and warm, I start noticing a little buck when I am going down the road or accelerating at lower speed. However, when I am on the interstate at around 70 the bucking goes away and doesn't persist. But anything below that ill get a faint little skip. How do I remedy this skip going down the road? Going WOT usually gets it back on track but a minute later it will happen again. Here is a little back ground about the car and what I have done.

89 CRX HF
D15B6 all stock besides short ram intake and ebay header. No cat.

Things that have been replaced or accomplished:
-ENTIRE ignition system with new components. Has also been timed correctly via timing light.
-Fuel filter
-Cleaned ENTIRE EGR system from inside the head to the ports. EGR has been tested and works like a boss.
-Ran 1 can of sea foam and currently on a wal mart brand fuel injector cleaner bottle. It was properly stirred by swerving like a maniac on a back road.
-TPS replaced with NEW. It has also been set. (Runs like a champ when unplugged)
-Had an ELD CEL. Replaced alternator with a bigger one and its hasn't came back. The CEL was intermittent at the time. ELD was tested and the last test that required the lights on, came out bad according to a test procedure on Honda tech. It read 4 volts instead of 2 volts. I DID have the battery tested a month back and it came back with the alternator at high voltage. I have yet to test the alt again for high voltage since yesterdays replacement.
-PCV valve is NEW
-Vacuum lines are NEW
-TB, IACV, and EVERY sensor has been cleaned or inspected.
-Injectors were shot with carb cleaner, but it wasn't ran through in a DIY method. They were NASTY at the outlet tips but the inside looked ok.
-Added ground from shock tower to intake manifold with 10ga wire. All other grounds were checked and cleaned.
-Tried a known good ECU and still no luck


Things that have not been tested or replaced:
O2 sensor
MAP sensor *tested but I haven't tried another one*


I am currently fresh out of ideas. I am leaning towards a set of REALLY dirty injectors but after all the cans of injector cleaner that I have ran have not helped. The person that had it before me drove it 358k miles (engine rebuilt at 340k) like a total granny and NEVER blew any of the crap out the injectors every once in a while. It also runs VERY rough for the first 5 seconds when I first crank it up in the mornings. Earlier it was hard to start and ran on what felt like 3 cylinders and eventually got over it. That was the first time its ever done that. I have NO CELS at this point and none are stored. I just don't know what else to do at this point. I would send the injectors off to be cleaned, but Rock Auto has rebuilt ones for around $25 a piece. It costs about that much just to have each one cleaned. I normally don't post on forums with a broad selection of applications, but I figured somebody here could help me with my problems since its a gas mileage model and a lot of people have them here. I can't seem to get any advice from CRX Community. All help is very much appreciated.

[GasSavers_Erik]

Maybe a weak fuel pump, bad/clogged injector or a bad oxygen sensor.

Since you mentioned that it ran poorly when first started in the morning, I would lean toward the fuel pump since the oxygen sensor signal is not used by the car until the sensor gets warm enough to go into closed loop.

Maybe you can put a pressure gauge on the fuel line to read what pressure the injectors are getting.

A bad/dirty injector would explain the way it seemed to run on 3 cylinders.

Have you done a compression test to verify that it has good compression on all 4 cylinders? (someone could have made a mistake during the rebuild)

How do the spark plugs look? All the same?

[shag wagon]

Well seeing as how the car has 360k and being as old as it is, Im sure somebody has replaced the fuel pump at some point but I could be wrong. I have seen o2 sensors cause a rough idle and very poor economy, but my last tank was right at about 46mpg 75% highway and 25% city. So I would like to eliminate that issue. I also want to say its definitely not a compression issue or else it would skip and carry on all the time. To explain my condition more, I can be going down the road and all of a sudden it feels as if I ran out of gas and it starts choking really bad and then when I go WOT it will catch back up and keep going until it does it again. I have been on a 2 day "Italian tune up" status with the fuel injector cleaner and it seems that it doesn't help at all. When I had the intake manifold off over the weekend, the runners and intake ports were clean as a whistle.

It is possible to access the fuel pump by a cover in the rear cargo area? I haven't had a chance to look and see. I know most Civics do.

[shag wagon]

Ok I have about a gallon and a half until im on E. I poured some of that B12 Chemtool in the tank and I ITU'd it again. It didn't do it this go around but Im sure by the time I hit the interstate thats 3 miles away from my house itll start being a **** again. I took the injectors out before I put the B12 in and checked the screens inside them. You can see some dirt but it wasn't enough to make em mad I don't think. I also poured the cleaner straight into the fuel rail so that it gets a good hit once it fires up.

I also want to point out, it does NOT have a hard starting issue if it is warm or warm outside. I have noticed it only does it when its cool outside and the engine is stone cold. It could be 90 outside and have a stone cold engine and it won't do it. But at about 75 or so outside and it will stumble a good bit before "catching up" so to speak. I am also going to see if I can get my paws on a known good fuel pump and try to change that out to see if it helps. I don't see how a fuel pump can get "weak" but Ill try it I guess. They are supposed to work or don't work. Not half work.

[GasSavers_Erik]

I don't know about the 89 CRX, but the fuel injected 85-87 crx and 86-87 Integra had an external mounted fuel pump- underneath the car under a cover just in front of the rear tire on the driver's side.

How about the appearance of the spark plugs?

[shag wagon]

I will check the spark plugs tomorrow. I will also be pricing a new fuel pump because I have noticed that people with the bad fuel pumps are having the SAME problem. But first I am going to get me a pressure gauge before I drop the tank to replace the pump

[imzjustplayin]

get an ohm meter and with the help of the service manual, find all of the electrical grounds and measure their resistance to battery ground. (Negative to battery negative) using the OHMs function. If you find your resistance is higher than 0-1ohms, then you should clean/repair the affected electrical ground, though you should do the battery's electrical ground first. Dirty/damaged electrical grounds can cause this.

[shag wagon]

All grounds have been recently cleaned or replaced. I just changed the thermostat and of course I had to take a ground off to get to that and I hit it really good with sand paper. There is a new ground cable from the battery to the transmission, brand new ground from driver shock tower to intake manifold, and all the ones I could find have been cleaned or inspected. The only one I haven't touched was the the fuel pump ground. I need to take everything apart back there and look down the in tank for any trash build up.

[shag wagon]

Ok so I took the plugs out just now. 1-2-3 are near white or VERY VERY VERY light tan. 4 is a solid tan. Im about to hook up a fuel pressure tester on the pressure release and see what it does when I am driving. But seeing as it only does it when its warmed up, I am leaning towards the o2 sensor now because it would skip all the time if it was a fuel pump I would think. And going to WOT gets rid of the issue because it shoots more fuel. That will be next on my replace list.

[shag wagon]

ok fuel pressure was checked and it jumped up to a solid 27 psi which I think is a little below normal but its a cheap harbor freight unit so its probably off a psi or 2. It never came down it started to skip and never even budged the tiniest bit. So according the gauge, we have proper fuel pressure or at least enough to say its good! Off to advance auto to pick up an o2 sensor. If that doesn't fix it, then I will be off to find a MAP sensor.


Speaking of MAP sensors, these are EXPENSIVE and HARD TO FIND for these cars. Here in SC you can't even find a CRX or Civic in the scrapper anymore thats not stripped to a bare bone shell. However, 90-93 Accords are plentiful down here and not stripped too bad. The map sensors on these cars are similar but has a different plug. If these are of similar make up, this would be a great alternative to having to find a map sensor for an EF Civic. Anybody know?