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Swapped instrument cluster, query about idle

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Swapped instrument cluster, query about idle

Postby deathmonkey » Tue Jul 10, 2012 7:18 am

Hey guys, I got a cluster out of a '91 civic ex hatch automatic and swapped it into my usdm 91 dx hatch after all my dash lights that aren't idiot lights quit working(wasn't the bulbs, fuse, brightness controller wheel, or wiring). It works fine but I think I've read something about the stock tachometer not being very accurate below 3k RPM. I have observed the same. Is there any way to make it closer to reality, particularly at idle? My little $30 aftermarket tachometer reads around 700rpm at idle when the stock tach reads 0.

I have one more question about idle. When my headlights are on in the city and I brake the idle drops from ~700RPM to ~500 RPM and gets lopey/crappy. It drops a bit during the day without headlights under braking but not like it does at night. What might this be indicative of?
I didn't see how to list location in a very limited exploration of the user control panel, so I live in Arkansas. Geographically it's in the southeastern United States.
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Re: Swapped instrument cluster, query about idle

Postby el_jelly » Wed Jul 11, 2012 2:14 pm

Check the wiring of the battery and the alternator, also check the main grounds.
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Where most of the questions are already answered > Engine swap guide, FAQs and Index thread
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Re: Swapped instrument cluster, query about idle

Postby deathmonkey » Wed Jul 11, 2012 6:48 pm

Thank you. I think I'll call in a sick day tomorrow and do the big three upgrade and see where that gets me. I don't even have a sound system installed right now so I didn't think it could be wiring. I had my alternator tested a while back but I guess if big three wiring mod doesn't take care of it I'll swap the alternator.
I didn't see how to list location in a very limited exploration of the user control panel, so I live in Arkansas. Geographically it's in the southeastern United States.
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Re: Swapped instrument cluster, query about idle

Postby TechGuy8 » Wed Jul 11, 2012 10:43 pm

deathmonkey wrote:Thank you. I think I'll call in a sick day tomorrow and do the big three upgrade and see where that gets me. I don't even have a sound system installed right now so I didn't think it could be wiring.


Before changing the big 3 cables, I would test the wiring first.

1. Start you car running.
2. Turn on headlights and A/C.
3. Use a voltmeter to measure the voltage across the negative battery terminal (not the connector to the battery terminal) and the alternator case. If you get more than 0.5V, you have ground wire problem.
4. Use a voltmeter to measure the voltage across the positive battery terminal (not the connector to the battery terminal) and the alternator positive terminal. If you get more than 0.5V, you have positive wire problem.

I had my alternator tested a while back but I guess if big three wiring mod doesn't take care of it I'll swap the alternator.

Don't trust the alternator testing machine. My alternator was not completely failed. Its output voltage was lowered when hot. Two different make and model alternator testing machines said it was working. Instead of changing the alternator, I changed the battery. I was planning to change the big 3. Before changing the big 3, I clean the ground wire connections and the positive wire condition. Tested the wiring using the above procedure. The voltage drop was 0.1V on the positive and ground wire. I came to the conclusion to change the alternator. My problem went away.
The thread on my alternator problem ==> viewtopic.php?f=8&t=13008
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Re: Swapped instrument cluster, query about idle

Postby deathmonkey » Thu Jul 12, 2012 11:49 am

Thank you very much. I ordered a new alternator and it's being shipped to the ancient man that still rewinds alternators. He thinks he can bump it up to 80A so I gotta upgrade that wiring anyway. I have a sneaking suspension that it'll be sorted out after beefed up alt and wiring.
I didn't see how to list location in a very limited exploration of the user control panel, so I live in Arkansas. Geographically it's in the southeastern United States.
deathmonkey
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Re: Swapped instrument cluster, query about idle

Postby WhiteDX » Wed Jul 18, 2012 9:00 pm

Could the reduction in idle be caused by a vacuum leak? Mine was doing the same thing when i turned on my lights, applied my brakes, or used my heater, etc. My RPMs would drop, and would start fluctuating. I noticed that when the previous owner installed the intake box on top of my TB (Stock B15 and stock intake), that they actually had the grommet that goes on the TB all twisted and out of place. Once I fixed that my problem went away. Just an idea while you are waiting on your alternator...Sorry, I am horrible with all of the technical terminology.
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Re: Swapped instrument cluster, query about idle

Postby deathmonkey » Fri Sep 07, 2012 1:01 pm

Yeah, it was the throttle body gasket affecting the idle. New alternator is putting out about 18 more amps than stock.

Now I have a new problem :angryfire:
My radiator fluid is going somewhere and it isn't going into the oil or vice versa. I'm pretty sure it's the lower radiator hose because those hoses appear to be original, however I've only ever observed the leak once. I seem to be overheating. I was in gridlock the other day in 100F and humid weather at about 3:15PM and started to climb over normal operating temperature. I hit the Interstate where the temperature dropped but then started back up and down again and again. When I got home it took about 3/4 quart of coolant to top her off. I let it sit for a couple days until yesterday morning I drove it a whopping 3 miles round trip to get breakfast without issue. Last night I drove about 6.5 miles, stopped and kicked it with a friend until this morning and then drove home 6.5 miles. When I got off the freeway and was hooning it a bit on a residential side street the temperature started to creep up so I gunned it to get more air flowing over the radiator. This half-assed worked. The max it got to was about a half inch from the maximum mark on the temperature gauge. (cluster with integrated tach). More air over the radiator didn't really help. When I got home I shut it off and turned the key to "II" i.e. the last click before firing the starter that turns the fuel pump on/all the other crap. The temp read completely normal not even 12 seconds after peaking at near the maximum.

I want to murder this problem with an obscene violence. Besides all the hoses in there, timing belt, thermostat, and water pump, is there anything else that would be wise to do? I replaced the coolant temperature switch last summer when my electric fan quit working (that fixed the fan) so I don't think I need another one of those. Any input here would be awesome.
I didn't see how to list location in a very limited exploration of the user control panel, so I live in Arkansas. Geographically it's in the southeastern United States.
deathmonkey
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