Phantom240

I picked up a '92 LX sedan from an old lady yesterday to keep miles off of my other car. The car seemed to run fairly well, but seemed like it needed a tuneup because it felt fairly low on power and had a slight hesitation once in a while. First thing I did when I brought it home was change the wires, cap, rotor, and plugs (as I do with any new acquisition). That seemed to help a good bit. However, I went to fire it up this evening to shuffle some cars in the driveway and it took unusually long for it to fire up. It spins over fine, but took 8-12 rotations to catch, and when it did fire up, it wanted to bog when I gave it gas. If I held the pedal to the floor, it would bog to about 500rpm, and you could hear it misfire. After about ten to fifteen seconds though, it is back to business as usual.

A little background on the car:
92 LX, D15B7, 403k miles. Yes. 403k. No smoking or valvetrain or injector clatter either. She's had the car maintained by local shops for the last five years. I sifted through the service records and receipts all the way back to 2009 (not even a quarter of the way through) back when it had 250k-ish miles. She traveled across country numerous times to visit her kids, and commuted 60+ miles to work every day. No major oil leaks, no accidents, 100% bone stock down to the factory 13" steelies and sawblade hubcaps. The clutch engages fairly high though. The car needs an alternator, because the battery light flashes over 4500RPM and the headlights dim when that happens. It's probably toast because she had a bad problem leaving the dome light on and killing the battery, which she's had replaced every other year. The alternator was replaced in 2010, nearly 150k miles ago.

So here's what I'm thinking:
-CEL not illuminated. Yes, it functions.
-IACV cleaning and a good seafoam treatment should be done with any used Honda purchase
-Check AIT
-Check ICM/Ignitor
-Check oxygen sensor
-Check mechanical and electrical timing


Any other ideas?

White_EG1

I wouldnt seafoam a motor with such high mileage. When you clean out the IACV clean the FITV too, its right under the throttle body.

Former User

Post any CEL codes and compression test the cylinders.

Phantom240

Would there be any CEL codes if the CEL isn't on? Not trying to be a smartass, I'm genuinely asking lol.

Aside from possibly throwing chunks of carbon into the cat, is there any other reason why it would be a bad idea? Admittedly, the oldest motor I've foamed was only 280k.

SpokaneSpeed

If compression/leak down numbers are good, i would try replacing the ECT sensor. This affects cold/warm starts.. the test procedure isn't very good for these so for the money, I usually just replace them if I think it's the culprit.

No, if the CEL is not on, it will not have any "stored" codes.

Phantom240

I'm trying to remember where my compression tester is at, lol.

Former User

This comment presumes that the CEL actually works. OP, do you know the answer?

This^ is the reason that compression testing the cylinders is critical at this point.

Some chain auto parts offer free rentals.

Phantom240

Yes, it works. Like I said in the original post, lol. When I turn the key to run, it comes on for a few seconds then shuts off.

None of the local parts stores have any in their rental fleet. I really need to find mine though, it's a nice craftsman unit. If nothing else, a cheapo from HF will suffice for $25.

Though I need to clear out some space in my garage to pull the front of the car in.

White_EG1

google

Phantom240

Just realized when started cold, it doesn't idle up like a normal Honda. It just starts and idles at it's normal 700ish, even after sitting overnight.

Former User

If a low idle is the problem, then you should be able to keep the engine running by pushing on the throttle pedal.

Phantom240

It idles fine, but pressing on the pedal results in bogging down, unless I wait a good ten seconds or so after starting it. Luckily, I have tomorrow evening off, so I'll have time to do some troubleshooting then. I've been working all weekend so no time.

Essentially, this is how the car operates at cold start right now:
-Turn key to run, CEL comes on then goes off as it should
-Crank engine
-Engine fires after 8-10 revolutions
-Engine immediately idles around 700-800 as if it is warmed up
-Press gas pedal, engine bogs
-Wait about 10-15 seconds, car behaves like normal, but continues to idle at 700-800.

No CEL code.

Former User

That's not an idle problem.

Phantom240

I appreciate your effort and the knowledge you're sharing, honestly. However, I think we're on different pages. The car idles fine, it just doesn't idle high like it should when warming up, which I believe to be an indicator of an issue with the control system or a sensor. Also, the main issue is hard starting and bogging until it is warmed up.

Former User

Check the ignition timing.

TomCat39

FITV under the throttle body controls cold start fast idle and is mechanical thermo controlled, no electronics to it.

After you check your mechanical and ignition timing, the FITV is the next thing to affect your cold start idling behavior on the 92-95. They removed the FITV and incorporated it's function into the EACV/IACV from 96 on.

It really sounds like your FITV is not functioning properly. But first you have to make sure the basics are okay (timing).

As for seafoaming the car. Many times on that high of mileage it's the varnish and carbon holding the compression into check so the motor runs. You clear all that out and it can potentially drop your compression below minimum spec and make the car no longer able to run.

Phantom240

Temp sensor was the issue after all. Of course, the alternator still needs replacing.

TomCat39

Glad you got it sorted, I take it the sensor functioned well enough to not throw a CEL but not well enough to have the ECU maintain the proper idle?

Phantom240

I honestly don't have any idea what kind of parameters the ecu operates with, so it would be pure speculation.

Phantom240

This car has me stumped, and I'm ready to just rip the motor out and rebuild it from the ground up. I'm having an intermittent issue with the car wanting to bog when accelerating at low RPM. By low, I mean under 1200. The problem is worst when trying to accelerate from a stop. I start letting out on the clutch, and if I give it too much throttle, or the engine speed drops below 800 or so RPM, it falls on it's face and drops to like 400rpm. Then it takes forever to start accelerating, but once I'm accelerating, it is more or less fine. It has stalled on me a couple of times like this, and no, I'm not just bad at driving stick. I've been doing this for 14 years. Another strange thing I noted is that when I let off the throttle, the idle comes down to 1000, then rises to around 1200 before settling back down to its normal idle. Sometimes it will hit 1500 and drop like a rock, kinda like the typical surge, but it will only happen once. This leads me to think it is a vacuum leak I haven't been able to find yet. I've linked some videos at the end of the post as well.

The car is a '92 EG LX Sedan with D15B7

So here's what I've checked so far:
- Changed plugs, wires, cap, rotor, and fuel filter when I bought the car a few months ago
- IACV was bad, so I changed it about a month ago
- FITV looks almost brand new inside, so I didn't completely disassemble it
- Fuel pressure is 35psi at idle, 44ish with the vacuum line disconnected. Opening the throttle brings it to about 42psi.
- Timing is set to 14-15deg BTDC
- Only CEL is code 41, though I caused that. The problem existed before I caused the CEL code.
- Haven't checked compression, as the problem is intermittent. Also, I can't find my compression test kit.
- The problem seems worse with the a/c on. Then again, the D15B7 produces 0 torque.
- TPS readings are in spec.
- Changed PCV at the same time I did the IACV, however the top of the hose crumbled when I removed the valve. I wouldn't be surprised if the hose (going to the breather chamber) cracked elsewhere and is causing a vacuum leak, however soaking it with carb cleaner didn't change the idle. The hose coming from the PCV to the intake manifold is now collapsed looking. I have both hoses and the PCV coming to me from Honda, and will be replacing them as soon as they arrive.
- Grounds seem solid, secure, and not corroded to death. Alternator produces 13.9v at idle.
- Checked base idle by disconnecting IACV, base idle was about 650 with no load.
- Changed coolant temp sensor
- Bled coolant system twice.
- Throttle body is clean as a whistle, and throttle plate isn't sticking.

Civic falls on it's face when accelerating from a stop. I gave it too much throttle, apparently.

Playing with it at a red light. You can hear it bog when I stab the throttle.

You can see that the idle hangs a bit, and I do get it to surge a couple times.

White_EG1

For the surging idle do a idle relearn procedure.

Phantom240

Doing the idle learn now.

Anyone else have any ideas?

TomCat39

First off, I don't see a bog, I see the typical low power/low torque at the low rpms as is typical of the D15B7, the torque bump is when it hits 4000 rpm.

I am seeing it struggle to return to idle. You might have a sticky throttle plate. My idle would get stuck near 1500 rpm after a nice WOT pull. Found my throttle body is dirty as well as the throttle plate shaft. I spray a bunch of throttle body cleaner down my throttle body, especially at the shaft junctions inside. Then spray the outside throttle cable bracket and spring with brake cleaner. No more sticking. Then I replaced my FITV and IACV and it's been relearning the idle and is working properly again.

I too own a D15B7 but with a 5 speed manual.

Even with a short ram, dry flow air filter and a decent 4-2-1 2" header with 2.45" piping the rest of the way back, the d15b7 just slowly climbs the rpm until it hits 4K and then just jumps until 5200 and then is maxed out on power and continues the linear or no climb depending on load. I live in a mountainous region and I can lose speed in 4th gear even at 5000 rpm on some of these hills.

Phantom240

I disagree. There's no reason why when I press the throttle to accelerate from a stop, and the engine actually slow down instead of accelerating. I'll clean the throttle body again just to make sure it isn't sticking.

TomCat39

In the videos I did not see the rpm dip only climb. But then again, the video unless it's overly dramatic won't show what you see and feel in the car.

Is this an automatic or a manual? Also, how long have you had the car? Was it better than before or are you just thinking it should be better than it is?

And if you think there is an issue, it sounds like you either need to find your compression tester or buy a new one. They are pretty cheap.

Another thing that can bog the motor is if it's sipping coolant.



The above dyno is an almost identical setup as mine except it's a CAI while mine is a short ram.

However the torque peak is just like mine and the power output is just like that.

As you can see right around 4300 rpm the torque suddenly jumps where it's been pretty flat lined for most of the climb and wasn't even really present until after 2000 rpm. The power is coming from less than half until it it hits about 4300 rpm and jumps with the torque, then by 5200 rpm the torque falls off and basically begins declining as well as the power just pretty much flatlines until rev limit of 6800.

From about 4300 to 5200 you feel a nice jump as both the torque and power are surging through that stage.

Before 2000 rpm there is very little power or torque and so when you go WOT it begins the slow powerless and torqueless climb.

You want more, you need a bigger engine or bigger cams etc.

And if you are an automatic you are also screwed being you can't raise your rpm before you load the motor. That's why the manual can feel much sportier. You can bring the rpm up to 2500 as you engage the motor. Or even do wheel hop by 4000 rpm dumping of the clutch.

With an automatic, the motor is engaged from 750 rpm with less than 50 ft-lbs of torque and less than 25 hp at the wheels. Disagree all you want, your motor on an autotragic is gutless until 2500 rpm or so.