LEATHL EG

Where should I start...

This has been the all time worst and definately most costly problem I have faced in the six years I have owned this car.

The idle is constantly surging between 1500 and 2500. I start the car and it may take five or maybe 15 seconds for it to start, but it has been doing this since before I put her up last winter.

Here is the background on the car:

It's a '93 Civic Coupe DX with a swapped D16Z6. Last year when I was stuck in traffic, I noticed that it was over heating and it managed to get to the point of boiling over and off the top of the temp guage by the time I could reach a spot on the highway to pull over. The radiator was toasted and the fan for what ever reason was not kicking on when the temp would get high.

After this happened I decided to put in a GSR radiator and a FAL fan to avoid any further cooling issues. The day that I did this my car began it's trip down idle surging lane. I initially thought that it was air in the cooling system and I bled it like ten times and couldn't get all of the air out. So, I took it in to the dealership and had them do a professional coolant flush. They told me that they couldn't pressurize the cooling system and that I had a blown head gasket. Great!

Since then I had the head checked and it wasn't cracked so I had a valve job and the head milled. I replaced all of the gaskets with a head set. This was not the problem. I have checked cam timing, it is absolutely perfect, and there is no chance of air getting into the cooling system from the head.

This is what I have replaced or bought since then:

ProFlo Throttle body (59mm)
TPS
MAP Sensor
O2 Sensor
Distributor, Cap, and Rotor
MSD SCI Ignition, Plug Wires, Coil
Timing belt
Alternator, and belt
Battery
Colored Hose kit (hoping to eliminate a vacum leak)

The error codes we keep getting when we short the ECU are seven and three. Someone told me that those are the TPS and MAP. Which I have already replaced. Is this right? I don't have a place to check error code numbers. One time we got a fourteen, but that was after we switched around the wiring harnesses for the TPS and MAP.

I have taken it to like five different mechanics and no one tell me anything. They all wind up blaming it on this extra wiring harness that is hanging off of the firewall next to the TPS. It is just and extra harness that was left over from the 1.5 that was in there before the swap. Just to clarify the swap ran fine for two years before this all went down.

I have no idea what else to do and I have already spent like $900 dollars in the last two weeks alone. If some one could give me any help I would seriously be in debt to them for the rest of my life.

Thanks,

Kyle

LshatchTurbo

Might be time for a new Main Relay.

LEATHL EG

Not to sound terribly stupid, but what exactly does that do?

LshatchTurbo

After about 8-10 Years, the electrically connections go bad. This relay controls power to the ECU, and the fuel pump. Its important cause without a current amount of power to the two, symptoms you describe could occur. Here is some more info on a Main Relay:

http://www.markl.f9.co.uk/howto/elec...main-relay.htm

Thats a okay site with some info. Its a dealer Part which will run you anywhere from 30-40 bucks. This could be the culprit hopefully this helps

LEATHL EG

Thanks, and I will give that a try tomorrow. At this point anything is worth a try! I am just hoping that enough people will reply that I can cover all aspects of what else could be wrong. I had to Auto X this weekend with it acting that way and it really sucked. Every time I take my foot off of the gas the car decellerates way to harshly. It's not the usual coasting feeling like you would have in a low gear, it's more like a bucking feeling. If you think of anything esle that I can try, I will be glad to try those as well.

Thanks again!

CunninLynguist

Thats almost exactly whats is happning to my 94 si, does any one know how to fix it!

LEATHL EG

What have you tried already..? Are you getting this at idle only or can you feel it in your throttle while driving also?

iriemark

iTrader: (1)

same thing happened to my 97 coupe... i thought maybe it was just a lose hose or something on my intake manifold but found out it was pcv valve (or something liek that). anyway, the vavle was opening and closing as if i was on the throttle. it cost me close to $300 to get it replaced... runs like new now and idle is so much smoother. hope this helps.......

CunninLynguist

Well i am not getting any codes...and i have tryd pretty much nothing, messing with the screw on the throttle body, looking for crack hoses and any that were disconneced...

Spoolin12s

sorry i dont frequent this forum lately.... but i have a crx with a DOHC ZC and my surges at idle also... but it does that because my Idle control valve is f*cked up... it is the thing on the back of the manifold, the closest thing to the firewall, and it has a connection for the sensor and 2 coolant passages... i know some engines have this in the TB... but you said you have a z6 so it is on your manifold... i would check that out and possibly replace it... i bet that is the problem.

kikicamacho

I've experience similar problems in my wifes 94 Civic LX Sedan w/ the stock d15b7 engine. I'll check the PCV valve and that idle control valve. I can feel it surging while driving, it really sucks.