*FIXED so simply* '88 240 down on power and getting really poor gas milage. Topic is solved

[MisterBobbles]

I figured up about 11 mpg at last fill up. 14 mpg before that.
No power off the line, but never had much, but this am seemed weakly going up a fairly significant hill.
Idle a bit rough, but always was. Otherwise runs great.

Any ideas on where to start before I load the parts Canon?

What I know:
Plugs have less than 10k on them. Wires and all look fine.
New MAF less than 6k. NOT OEM
New O2 sensor 2k ago. OEM
New fuel pressure regulator switch thing under dash( fixed a occasional no start for 16 bucks.)
New timing belt 20 k ago ( not by me).
Newer fuel pressure control valve thing on manifold ( not by me, think OEM.)
no fuel in vacuum hose.
New fan clutch last few weeks.
A/C recharge same time.

I haven't pulled plugs or done anything but check leads and hoses and connections.
Not sure where to start, and don't want to overlook some simple thing I'm missing whilst replacing a zillion perfectly good working parts.
Again, he runs great, starts fine. Just a thirsty dog off the line who thinks I own a gas station.
Any help and direction is greatly appreciated. I love my car.
( Have billions worth of OEM front suspension parts for this falls rebuild project. I sold a kidney.)
Thanks in advance.

[volvolugnut]

Pull all plugs and check gap and color. Easy to do and will tell you what is happening. I expect they are black with excess fuel. Maybe only one cylinder - then check that injector. Injectors can wear out and start to dribble excess fuel.
Put a fuel pressure gauge on and test. Should be 44 PSI.
See if the fuel pressure regulator is leaking fuel into the vacuum system. Sniff the vacuum hose for fuel smell.
Check your ignition timing with a timing light. Should be 12 degrees.
Check for vacuum leaks.
How many miles on engine? Do you have a manual with maintenance info?
volvolugnut

[MisterBobbles]

Thanks volvolugnut. I will check all this a.m.( Sat morning my time).
I was hoping someone would write " oh, easy fix, just open gas filler flap, turn on left turn signal, place right palm on manifold while holding a Swedish kroner in you left, cross your ankles and recite these words...."

But alas, no easy fix. I just pray it isn't that horribly frightening computer box I dare not even look at lest it take offense.

Because My thought was timing, but I didn't know if ,or how much, I can control or effect the balance of fuel air spark ratios without upsetting the computers deal, and I don't want to throw the car into a worse state.

I'll check everything and get back.

Oh: 161,000 miles, no manual.
Thanks

[volvolugnut]

Find and buy a manual.
These 240s are tough and hard to kill. But they are different and need special attention to their fuel and ignition systems.
volvolugnut

[MisterBobbles]

OK,
Pulled plugs, they don't look bad. Not what I expected.
There's holes in the accordion tube from maf to throttle body.
Could that make this drastic of a difference?

I don't think I have the kjet system, as that started in '89, and I don't have the control box on the firewall next to the brake booster that has. I have this(pic) scary box of magic.

Can you tell me which manual to get?
Thanks

[MisterBobbles]

Also, what is this thing near the block? Some air control thing. ????

[volvolugnut]

Yes! Tape up the tube and retry. I had this problem once and I think it would not start.
If it gets better, buy a new tube.
KJet system was older, pre 1983. My 1975 245 had KJet. My 1983 245 did not.
Haynes Volvo 240 series manuals are good, cheap and were plentiful.
Bentley Publishers Volvo 240 Service Manual is Best, but maybe $50 online. Lots more trouble shooting and schematic info.
Your plugs look great. Excess fuel is not likely going through the cylinders. Look for a leak in fuel system? Rusty lines?
volvolugnut

[MisterBobbles]

Thanks. I'll let you know.

[volvolugnut]

Check your plug gap. It looks big. Should be 0.028 to 0.032 inch. They also look worn on edges.
A fuel leak would not explain loss of power unless leak is on pressure side and you have low fuel pressure at the fuel injectors.
volvolugnut

[MisterBobbles]

Yeah, I think this is it. I stuck the Camara in there ( I don't see so well unless my face is right up to something) and there was old tape there. The started lead is rubbing it.
Gonna pull it and epoxy, ( plus get a new tube of course) and see.
Did you see the question and picture about the thing on(near ) the block? What is that?