DoritoMan72

Hey guys, about six months ago I bought myself an 88 FC. When I got her, she idled well, but I noticed a distinct lack of power, very sluggish especially in high rpm ranges. Well, after some research I took apart the exhaust and found that the first cat had exploded and clogged the whole system. I hollowed out the cats and at the same time replaced the stock airbox with a cold air intake. While doing this I damaged the stock AFM and had to replace it. Ever since that change I've had a significant boost in power and efficiency, but she runs rich at idle. She can't hold a steady idle rpm and she spits fire under 1000. Sometimes she'll idle high at 1100 rpm for a bit, then misfire and fall to 500, then bounce between 650-950 until slowly achieving a rough idle. I'm not sure why this is happening. My first thought is the removal of all the cats left no back pressure, and that buying a new exhaust with the proper design would fix the issue. My other thought is with the increased air flow I'll need a new ECU and a tune to get the mix right again. I dont want to damage my engine so if anyone knows whats up please help.

diabolical1

iTrader: (3)

welcome to the board.

well, you said you bought the car about 6 months ago, so my first question would be are you sure the PO didn't do some weird modifications to the fuel system - injectors, pump, etc.

the next thing that comes to mind is maybe check the temperature sensor at the back of the water pump.


Post # 10,000 ....

rlynchster

Yea. . .Change the temp sensor. You may have to pull the alternator to do it but it's a cheap part to change.

Next, get a hand vacuum pump and check the EGR valve and double throttle diaphragm. Most likely they are broken and will leak after all these years. Be careful removing the EGR vac line from the solenoid side. Always twist vacuum lines off the plastic barb or it will break.

Download the field service manual from foxed.ca and go through the fuel and emissions section like a bible.

Set the Throttle position sensor along with the Idle adjustment screw and variable resistor. . . . Do this following procedure in the manual. . set the TPS voltage first.


If this doesn't work start checking vacuum lines with the hand vacuum pump.

Get yourself a volt meter and check what you can per the manual. There are lots of things you can simply ohm out like the air intake temp sensor.

Buy some silicon tubing for the small vacuum lines cause most likely you'll need it.. . .change what you can easily.

Inspect the check valve behind the air control valve.. . .that's cheap and easy to change.

Use the starting fluid trick and look for sudden raises in RPM's