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Old 10-06-2002, 04:58 PM   #1
WRX-Hellfire
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Default Idle and overheating problems 4 days after installing injectors/fuel pump(long)

I am currently running into idling problems with my newly install fuel pump and injectors. I am not sure if it is the fuel pump or something else. Last week I finished installing my sti injectors with walbro gss342 fuel pump. Everything was fine for 4 days and then one morning the idle started to fluctuate. The rpms will fluctuate from the standard ~750 down to 300rpms or even stall out. This only happens when idling, WOT and normal driving work fine. I double checked the install and everything appears to be fine with the injectors and the fuel pump. I drove around a bit and then the car started overheating. It will never actually hit the hot level but will raise 3/4 of the way and then the fans kick in and it cools back down. I am ok on the freeway its just the lower speeds that has the problem.

I then removed the unichip and the idle settled down to normal but the car still overheats. I then contacted Turboxs and they had me mail back my chip/harness to have it checked out. They plugged my board/chip into one of their cars and it idled fine, then they ran the tests that they can and everything checked out. So I had them reflash it anyway just for the heck of it. I received it back and car will instantly have idle problems when its plugged in. I have had this chip/board since January with no problems what so ever. I dropped my car off at the dealer on Friday but there was not much they would do because of my mods. They checked out the radiator fans and tested for a blown head gasket. The fans were operating properly and it was a negative for the head gasket(thankfully). I have been told to replace the thermostat, which I am doing tomorrow. Hopefully that will solve the heat problem but I am still baffled as to why my car idles so badly when the unichip is plugged in.

My car also has started doing weird things with the speedometer, it will bounce around while idleing(+/- 20mph) and driving so I never know what exact speed I am going. Anyone have any ideas on what can cause this? This will happen even when the unichip is unplugged. Currently my car is not being driven at all until I start going in reverse on removing the parts to find out what the problem is.

Any have any ideas on any part of this? I am also curious as to what happens when you start to foul the plugs?(possibility?) And what a bad fuel pump can do.

My mods are basically on par with txs stage 4.
M2 tmic/exhuast/uppipe, GFB pulley/BOV, sti injectors, walbro gss342 fuel pump, vf 30 and colder plugs.


Thanks in advance for any who reply. I do have DD if I can check anything out that way.
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Old 10-06-2002, 06:41 PM   #2
Gaspipe
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Regarding the overheating, the only things that come to mind are:

1) Waterpump - belt slippage (check that belt)
2) Air pocket in coolant system (bleed the system)
3) Bad thermostat (change)

Regarding the idling problem, I assume you have everything plugged in and fitted and have double checked all that stuff. Since it idles OK without the Unichip, I'd be inclined to think something is not quite right there.

Lastly, take a look at those cooler plugs - you may have fouled them.

I'm baffled on the speedo. Perhaps a grounding or cold solder joint?
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Old 10-06-2002, 11:08 PM   #3
bamfwrx
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did you say that it runs ok with the stock ecu?
you know when one injector starts to drip teh ecu will see a rich condirion leaning out the engine only problem is now three holes are way lean and one is way rich. this will crack head or damage piston, on most engines not sure what is teh week link on ej20.

just a thought
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Old 10-07-2002, 01:14 AM   #4
WRX-Hellfire
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Quote:
Originally posted by bamfwrx
did you say that it runs ok with the stock ecu?
you know when one injector starts to drip teh ecu will see a rich condirion leaning out the engine only problem is now three holes are way lean and one is way rich. this will crack head or damage piston, on most engines not sure what is teh week link on ej20.

just a thought
bamfwrx
Car idles ok with the stock ecu and larger injectors, it will eventually misfire with all that fuel if I leave it idleing for too long. But the overheating problem will persist no matter with stock ecu or unichip.

Gaspipe
I did check for air pockets a few times hoping this is what is was but it did not seem to help. The dealer even made sure the system was full and did not find any air pockets. I am going to change the thermostat probably tomorrow or the next day. Should I go for an aftermarket one or just stay with stock?
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Old 10-07-2002, 03:12 AM   #5
whitewag
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if your going to change the thermostat... get the Zero Sports one, it's worked great for me
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Old 10-07-2002, 10:52 PM   #6
andygold
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Just a thought. If your fuel filter is clogged you might experience the crazy idle speeds, as well as the stalling, and the lean running conditions. Same thing happened to me on my old GTI when I replaced the fuel pump for a higher performance one. I'm guessing the extra pressure was pushing the dirt paticles harder into the screens, making it clog more efficiently.

Can't say this is your problem, but a change of the fuel filter helped for me. As to the wierd speedo issue, sorry, no clue.

Andy
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Old 10-08-2002, 12:04 AM   #7
fc3swrx
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Lightbulb Speedo cable?

Have you removed the speedo cable during the install of anything? It may have worked loose. My Rx7 did the same thing...It was just a little loose and caused it to give some bouncing readings.. Also I have had issue like this w/ a bad ground or battery cable. I'm not sure if the Uni-chip is taking readings from vehicle speed..

just a thought..
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Old 10-08-2002, 01:21 AM   #8
Austin
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The ECU recieves signals from the engine coolant temperature sensor, vehicle speed sensor, and A/C switch. According to these signals, the ECU turns ON or OFF the radiator main fan and sub fan simultaneously, and also selects the Hi or Low fan speed (for the turbo model).

First off, verify that your fans are operating as they should. As a temporary fix to your overheating problem, run the AC compressor. That will turn your cooling fans on regardless of coolant temperature.

Based on all your symptoms (especially your wacky speedo), I would suspect that your vehicle speed sensor is faulty. Your radiator fans are not turning on when they should because your ecu believes that your car is moving, when in fact it is stationary. That is also why your speedo jumps around.

There are 2 main fan relays and 2 sub fan relays. It is also possible that one or more of your relays have fried.
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Old 10-08-2002, 01:43 AM   #9
Austin
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Check VSS
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Old 10-08-2002, 02:01 AM   #10
Austin
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2nd half
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Old 10-08-2002, 11:11 AM   #11
WRX-Hellfire
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Post

Quote:
Originally posted by Austin
The ECU recieves signals from the engine coolant temperature sensor, vehicle speed sensor, and A/C switch. According to these signals, the ECU turns ON or OFF the radiator main fan and sub fan simultaneously, and also selects the Hi or Low fan speed (for the turbo model).

First off, verify that your fans are operating as they should. As a temporary fix to your overheating problem, run the AC compressor. That will turn your cooling fans on regardless of coolant temperature.

Based on all your symptoms (especially your wacky speedo), I would suspect that your vehicle speed sensor is faulty. Your radiator fans are not turning on when they should because your ecu believes that your car is moving, when in fact it is stationary. That is also why your speedo jumps around.

There are 2 main fan relays and 2 sub fan relays. It is also possible that one or more of your relays have fried.
I hate to admit this but the grounding wire on the drivers side was not tightened down all the way. I found this out late yesterday after doing more checks in the engine bay. Tightened it down and it fixed everything. Strangest thing I have ever seen. Shows how important the grounding wires are. I can now run around with the unichip plugged in and have no problems. I flogged it good trying to get the heat up in the radiator and no problems at all. Talk about a newbie mistake

Thanks everyone for their input
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Old 10-08-2002, 07:02 PM   #12
nmyeti
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Quote:
Originally posted by WRX-Hellfire


I hate to admit this but the grounding wire on the drivers side was not tightened down all the way. I found this out late yesterday after doing more checks in the engine bay. Tightened it down and it fixed everything. Strangest thing I have ever seen. Shows how important the grounding wires are. I can now run around with the unichip plugged in and have no problems. I flogged it good trying to get the heat up in the radiator and no problems at all. Talk about a newbie mistake

Thanks everyone for their input

I was just about to post... same thing happened to me. Glad you found it though.

-Nathan
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