stock 95 S14 w/KA throwing code 21 -- need help

[Mark95TT(ATL)]

Hi all,

I posted this at a "rival" forum but then thought I might get better response here. I need some help with my code 21. I've read the FSM on the topic and searched through the old threads here and elsewhere, and I'm still at a loss of what to try next. Here's my issue:

Car
1995 S14 SE, basically stock, 162k mi
stock KA, original motor
RSR ex-mag exhaust

Symptoms
Car starts and revs fine. Sometimes, while cruising or under decel, the car will "buck" very quickly, like it's not seeing spark for a second. Then returns to normal. I have rarely/never noticed this under WOT though, mostly cruising or decel. Also, seems to be "triggered" at times after I've hit a bump in the road, but definitely not always. And frequently I notice it under perfectly smooth conditions as well.

What I've tried
- installed new distr cap, rotor, plugs and wires for new OEM
- swapped distributor assembly (incl. ignition coil, power transistor, and cam position sensor) with one from one off a used S14 engine
- swapped out "resistor" with one from a used S14 engine
- cleaned all electrical connectors w/elec contact cleaner


Unfortunately, none of these things seemed to fix my issue . The only thing I haven't tried is checking continuity/grounding/impedance of all of the ECU wires which the FSM suggests. I can still try that although I've been told these wiring harnesses are pretty rock solid.

So I'm at a loss. I'm trying to sell the car and want to get it running right before doing so. Any help is much appreciated!

Thanks,
Mark

[Dream240]

Do you have the FSM downloaded?

If so start at page EC-105 and follow the diagnostic chart to see if you can isolate the problem. That's where I would start first.

Or....

If you've already tried another dist. assembly, and you're still throwing codes, pull the plugs after driving around for about 300-500 miles. See if any of them are soaked with fuel. If any of them are that'll help you zero in on which cylinder isn't firing.

It's possible that it's not ign related at all. could be a bad/clogging/sticking injector....?

Good luck.

[Mark95TT(ATL)]

Do you have the FSM downloaded?

If so start at page EC-105 and follow the diagnostic chart to see if you can isolate the problem. That's where I would start first.



Thanks Dream240. I do have the FSM. I've been going through the diagnostics it prescribes starting on page EC-105. I've gotten to "D" on EC-108, and I'm stuck. Where it shows the diagram for testing continuity between terminals b and d is where I get lost. I'm pretty sure terminal b refers to the ignition coil harness connector. I can't figure out what c and d refer to though. Which connector is that?

If it's the resistor, I can't figure out a way to 'unplug' the two wires connected to it. There's not really a connector, they just seem to be hard-wired in there.

Also, as a side note, I realized I mistakenly traded out the condenser today and not the resistor. So the resistor and/or it's harness may potentially be the culprit.

[sac]

just wondering, has the fuel filter been changed? the 95 i bought had a oe F.F. and it had 146k on it. Had OE plugs fouled to hell, cracking wires, rotor completely burnt and cracked etc.. I bought it in cali, drove to kragen, and put new ngk plugs, wires, Fram z32 F.F, and new cap and rotor. Before i did all of this it wouldnt idle properly, it would bounce up and down. After, it ran like a champ.

I think it would be a higher likelyhood that Dream240's suggestion would be more accurate though.

[projectRDM]

just wondering, has the fuel filter been changed? the 95 i bought had a oe F.F. and it had 146k on it. Had OE plugs fouled to hell, cracking wires, rotor completely burnt and cracked etc.. I bought it in cali, drove to kragen, and put new ngk plugs, wires, Fram z32 F.F, and new cap and rotor. Before i did all of this it wouldnt idle properly, it would bounce up and down. After, it ran like a champ.

I think it would be a higher likelyhood that Dream240's suggestion would be more accurate though.

Kid, I don't know what's worse, your repeated attempts to answer a question knowing you have no clue what the fuck you're talking about, or the actual answers you give that clearly define that you don't know what the fuck you're talking about.

Please tell us all how a clogged fuel filter can trip a primary ignition fault? I didn't know the ignition coil was powered by gasoline.

[Dream240]

Thanks Dream240. I do have the FSM. I've been going through the diagnostics it prescribes starting on page EC-105. I've gotten to "D" on EC-108, and I'm stuck. Where it shows the diagram for testing continuity between terminals b and d is where I get lost. I'm pretty sure terminal b refers to the ignition coil harness connector. I can't figure out what c and d refer to though. Which connector is that?

If it's the resistor, I can't figure out a way to 'unplug' the two wires connected to it. There's not really a connector, they just seem to be hard-wired in there.

Okay when you're looking at thiose connector pictures, the little picture with the T.S. tells you which side you should be holding onto. When it says H.S., that means your using the "Harness Side" or backside of the connector, and T.S. means "Terminal Side" or rather the open face side of the connector. Also check out the bottom of page GI-12 for an explanation of the difference between male and female connectors. To help "decode" the FSM check out the GI section(specifically GI-12). It has alot of helpful tips for understanding all the lingo and references in the FSM. I had to read this section quite a few times over the years to make sense of some of the diagnostic steps throughout the FSM.

As for the proper connectors, for both connectors plugged into the dizzy, see how one of them is oval and one is square? I can't remember off hand which is which, but you're going to be checking continuity from B on the oval connector to D on the square connector. Then check continuity from C on the square connector to the ECU harness connector terminal 2. you should have continuity in both tests. Oh and I'm sure you know this but, you're doing all these test with the connectors disconnected. Also try jiggling the connectors while you have continuity to make sure it's not just a dirty or loose wire in the connector.

Really most of the time it's a bad connector not a bad wire that causes shorts.

If you get good test results with that, then go to the next step which is testing the resistor component, EC-109.

Good luck.

[Mark95TT(ATL)]

Okay when you're looking at thiose connector pictures, the little picture with the T.S. tells you which side you should be holding onto. When it says H.S., that means your using the "Harness Side" or backside of the connector, and T.S. means "Terminal Side" or rather the open face side of the connector. Also check out the bottom of page GI-12 for an explanation of the difference between male and female connectors. To help "decode" the FSM check out the GI section(specifically GI-12). It has alot of helpful tips for understanding all the lingo and references in the FSM. I had to read this section quite a few times over the years to make sense of some of the diagnostic steps throughout the FSM.

Yeah, I was reading through that last night. I kept wondering what H.S. and T.S. meant. Took me awhile to figure out that with the ECU harness, the FSM refers to it from the T.S.

As for the proper connectors, for both connectors plugged into the dizzy, see how one of them is oval and one is square? I can't remember off hand which is which, but you're going to be checking continuity from B on the oval connector to D on the square connector.

I noticed the oval and square connectors in the picture. Problem is, I can't find the equivalent square connector anywhere on the harness! I thought maybe it was talking about a connector to the resistor, since in the previous step it tells you to strip the tape holding the resistor/condenser to the wiring harness. But the resistor appears to be hard-wired in, and the FSM never explicitly states what connectors these letters (a,b and c,d)correspond to.

So basically I'm still stuck trying to figure out where c and d are. Also, I don't know how I'll measure the resistance of the resistor (as shown at the bottom of EC-109) since it seems to be hard-wired. Thoughts?

[Dream240]

You're on the right track. The A-B connector is the ign. coil plug on the dizzy. And from what I can tell the C-D connector is the resistor plug. There has to be a way to unplug it. Just start squeezing the connector and pull on the resistor, it'll come off. That's your square connector.

I think we're on the same page but, when you see T.S. you should be taking the connector and looking at the pins. When you see H.S. you should be looking where the wires go into the connector from the back. Make sense?

Also as for the ECU, when you look at the picture at the bottom of EC-108, the ECM connector is telling you to test from the backside of the connector (H.S.) and C from the resistor connector (T.S.). That's how you understood it too, right?

Hope this helps.

[Mark95TT(ATL)]

You're on the right track. The A-B connector is the ign. coil plug on the dizzy. And from what I can tell the C-D connector is the resistor plug. There has to be a way to unplug it. Just start squeezing the connector and pull on the resistor, it'll come off. That's your square connector.

Hmmm. That's what I would gather too but I could swear the resistor is wired in. I'll have a look again tonight.

I think we're on the same page but, when you see T.S. you should be taking the connector and looking at the pins. When you see H.S. you should be looking where the wires go into the connector from the back. Make sense?

Agreed, that's how I've understood it.

Also as for the ECU, when you look at the picture at the bottom of EC-108, the ECM connector is telling you to test from the backside of the connector (H.S.) and C from the resistor connector (T.S.). That's how you understood it too, right?

OK. I was interpreting the H.S. and T.S. to mean just how they were referencing the numbering of pins, but not specifically implying that you have to test it from that side. I'll have a look at it though.

Thanks for the input.

[Dream240]

Usually when you test from the H.S. you are testing the connector with it plugged in, since that's the only way you could test a plugged in connector. If it's referring to the ECM connector as a H.S. it's just telling you that you don't need to unplug it to do the test. although I would just because you're already in there and it's better to test the connectors on both sides to see if your results change.

Glad to see that you're actually using the FSM to your advantage. You'd be surprised how many guys ask questions about diagnostics and they have never even taken a peek at the FSM for some starter help. While it doesn't answer all the questions all of the time, it has really good starting points for most problems.

[Mark95TT(ATL)]

Yep. I already had unplugged the ECU harness connector, so it was easy to get access to the terminal side. And yep, the FSM has helped me out many times in the past. Anytime I'm working on the car I at least pull it out to check torque specs on the important nuts and bolts.

[Mark95TT(ATL)]

Well, I finally made it through all the diagnostic steps from the FSM. I figured out that the resistor does not disconnect but you can get access to the wires from the harness side. Everything checked out per the FSM's specs.

So, at a loss of anything else to do, and since the problem seems like it might be related to a bad ground or wiring issue given the intermittent nature, I stripped back the tape on the wiring harness to the ignition coil and power transistor. I check for any signs of arcing (none), and re-taped everything with a thick layer of electrical tape. Also applied dielectric grease to all of the connectors on the harness. Double-checked the ground for that wiring harness as well. Then cleared my codes, restarted the car and took it for a spin.

But still NO DICE. Problem is still there, still throwing code 21. Any other ideas?

Thanks,
Mark

[Dream240]

Well you could try moving on to the injector side of things. Since you're getting good tests from the dist. the problem might exist in other components of the firing system.

I guess my next step would be to test the resistance on the injectors per the FSM, check your injector O-Rings, pull the spark plugs and look for signs of fouling (gas soaked, burning, etc).

You can also check all the engine bay grounding points. But don't just check for tightness, pull them off, clean them with a wire brush, clean the contact surface, apply some di-electric grease to the contact points. Make sure you're getting the best ground possible.

That's strange that the resistor doesn't disconnect. How do they expect you to replace it if it's bad? I've yet to have to pull one off an S14, the S13 was easy and obvious. hmph......

Hope this helps.

[Mark95TT(ATL)]

I guess my next step would be to test the resistance on the injectors per the FSM, check your injector O-Rings, pull the spark plugs and look for signs of fouling (gas soaked, burning, etc).

I didn't mention this in my original post, but I recently had an injector fail, and I replaced it, as well as replaced the injector o-rings on the remaining good injectors. The code 21 problem I'm having now actually pre-dated the injector failing, and I thought the 2 were related. But now that I've replaced the injector and the problem is persisting, I've been thinking otherwise.

Aside from those items, I recently changed all my spark plugs, plug wires, distributor, distributor cap & rotor.

You can also check all the engine bay grounding points. But don't just check for tightness, pull them off, clean them with a wire brush, clean the contact surface, apply some di-electric grease to the contact points. Make sure you're getting the best ground possible.

I will have to do this. On the one ground I checked today, I pulled off the connector, sanded it and the engine block where it contacts with sand paper (don't have a wire brush), but I didn't apply the dielectric grease there. I need to check the other ground spots though.

Thanks once again.