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Discussion Starter #1
Hey guys,

I recently bought an 87 Lancer with a T2 conversion from an 89 Daytona Z. The car randomly cuts ignition/power under boost but comes back to idle as soon as you let off the gas?? Amy ideas?

I was wondering if it was a TPS?

Thanks

Nick
 

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Unfortunately your issue could be caused by a lot of things.

1)Are there any fault codes stored in memory?
2)Does the problem only happen in boost and if so at what boost pressure does the problem happen?
3)Are there any other driveabilty issues?
 

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Discussion Starter #3
Good question, how do I check for a fault code?

Probably does only incur while under boost. However, no other driveabilty issues.
 

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From what you are describing it sounds as though you have an ignition problem or are experiencing an Overboost condition.
To check for fault codes...
1)Turn the ignition key on-off,on-off, on
2)The Power Loss or Check Engine Light will begin to flash, these flashes are the fault code numbers. All Codes are two digit numbers.
3)The first digit of the code will flash slowly, followed by a slight pause and then the second digit will be displayed by shorter/quicker flashes.
IE: Code 24 Two Longer/Slower Flashes followed by Four Shorter/Quicker Flashes.
4)The last code you will see is a Code 55 which is End Of Message meaning the engine controller is done communicating with you.
5)Repeat the procedure if you need to check the codes again.
6)Post back letting me know if there are or are not fault codes present and what they are.
7)You may have some codes that have been there from the beginning since the wiring harnesses are the same but the component may not be present,they are generally related to Torque Converter Clutch, Air Conditioning, etc, they are nothing to be concerned about.

 

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Discussion Starter #5
If I'm following, it appears to be five quick flashes followed by a slow sixth.

Also, the car only seems to buck if you go full boost quickly, the problem doesn't appear when you slowly roll in to the boost.

Thanks again!
 

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If I am understanding you correctly that would be a Code 51, recheck your codes again to be sure, did the code retrieval end with Code 55?
If that is correct Code 51 is a Lean Exhaust Indication which can be caused by anything that would create a lean fuel mixture, anything from ignition, fuel, sensor calibration, etc.

Do you have a boost gauge in the car?
At what boost pressure does the problem appear?
Does it happen at the same boost level everytime?

You are going to have to follow a logical diagnostic sequence to determine the cause.
I can lead you through this step by step.
 

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Discussion Starter #7
The bucking doesn't start at the same boost level, it is somewhat erratic. I do have a boost gauge and it sometimes starts around 5 psi and sometimes at full boost? I eas thinking of changing the fuel filter since I don't know when it was last changed.

I also have a new MAP, TPS and coil I'm going to install.

Thanks again

Nick Davis
 

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I cannot tell you what to do but normally throwing parts at a problem does not fix the problem.

If you would like to diagnose the problem let me know.
 

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Discussion Starter #9
I cannot tell you what to do but normally throwing parts at a problem does not fix the problem.

If you would like to diagnose the problem let me know.
I agree with you but I have a new thought. The P.O. removed the factory air box and installed a cone filter directly on the turbo. The car appears to have some type of MAF assembly in front of the factory air box. I'm assuming this would throw the entire AF mixture off if it's not having air drawn through the MAF? Just a thought since I know the 80's Mitsubishi heavily rely on the MAF to run correctly.

Thoughts?
 

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Would need a pic but our cars do not use a MAF, they use MAP (speed density) and the controllers are not designed or programmed to accept MAF.
Are you sure he did not install. BOV?
 

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Nick, do yourself a favor and follow NAJ's advice.

He'll help you pinpoint the problem without wasting $$$$$

Don't get ahead of yourself and you can learn some useful things.

It's a step by step process and NAG can skillfully take you through them.

Thanks
Randy
 

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Discussion Starter #13
The box directly beside the battery appeared to have been connected to the factory intake airbox before it was removed. See pics
 

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Discussion Starter #15
Great! At least we can rule that out. I also found an open port on the PCV loop and capped it. Idles much smoother now, hahaha
 

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That device installed in your charge tubing is a BOV (Blow Off Valve).
It relieves boost pressure left in the charge hoses between the turbo and throttle plate when the throttle closes otherwise the boost pressure pushes back on the turbo.
The BOV closes under pressure and opens with vacuum so as soon as you release the throttle it opens relieving boost pressure,that is what makes the "Whoosh" sound when you release the throttle.

I assume the original problem is still there.
1)When you are driving and the problem occurs what happens if you do not get off of the throttle when it happens?
a)Does it "buck/stop bucking, buck/stop bucking, buck/stop bucking" or does the engine completely stall and shut off?
2)Were you able to recheck codes?
 

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Discussion Starter #17
Alright gents, back at it. It's pulling two codes now. It's showing codes no. 23 and no. 24. On top of that it's gone in to limp mode and won't rev past 3-k.....

Any thoughts?
 

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Code 24 is TPS Voltage High (Open) or Low (Shorted), only a scanner will give you the exact code description.
You need to start by checking TPS closed throttle voltage.
1)With the key on/engine off, using a digital voltmeter backprobe the Signal (OR/DB) and Signal Return Lines (BK/LB) at the TPS connector.
ELECTRIC-TPS Connector 87-94.jpg
2)What is the voltage reading?
a)Below .20 volts?
b)Above 4.80 volts?
c)Other?

Post Back with the voltage reading and we will go from there.
 
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