My car.

Here's the stats:

87 Caprice, Computer Controlled Q-Jet.

Gutted AIR pump.
No belt on the A/C compressor.
Gutted AIR lines.
Blocked off a couple vaccum ports
Removed half the Evporative Emmisions lines, just made it simpler.
180 thermostat
Thermostatically controlled electric fans.
Edelbrock Performer intake
Rebuilt carb with Monte SS rods and hanger.
New radiator (stock replacement for my 79)
9"x2" open element K&N


When you floor it from a stop, it barely bogs, barely knocks, sounds like all my rockers are loose and then takes off slower than it should.

When you floor it at about 45 MPH, it bogs, pops (maybe a backfire, I never had a car backfire, so I don't know, it's not real loud.) and then takes off when it downshifts.

At idle, the transmission sounds like it has marbles in the pan. (This got better when I changed the fluid and filter, but not completely gone.)

The Early Fuel Evaporation valve (cast iron butterfly under the pass exhaust manifold) was shot, so I moved it to the open position. (Which I sure hope is all the way counter-clockwise.)

I'm not going for a dragster here, this is my daily ride, just want it to run well, and it isn't at all.

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Shane McConnell[*]Webmaster of www.NEThirdgen.org[*]1991 RS 305 T5 15.6@88[*]1979 Z28[*]1987 Caprice

 

I need to double check the timing, but it's not far off, I have it set by ear right now, it's at the best time I could set it at so the car would idle, it doesn't wanna idle low at all. it's 1000 RPM all the way, 1300 before the carb/intake swap.

And it's not dieseling anymore, so I think the old carb was the source of the vaccum leak.

Plus, GET THIS!

There was SEVEN QUARTS of oil in the engine when I chenged it! WTF!

 

Oh, it has new plugs and wires, I do wanna check the ignition module, and I need new coil wire. B ut the coil wire is working for now, I just wanna change it as a preventative measure.

 

Mac,

The transmission noise could be nothing. There was a TSB for TH700-R4 trans oil pumps making a "buzzing" noise at warm idle when in gear or not, but more frequently in gear. The problem is that the pump at such low RPMs with hot, thin trans oil could not flow enough to keep the oil pressure regulator relief valve from hammering on its seat, trying to modulate oil pressure from a barely-turning pump. If you slightly increase the idle speed, the noise should disappear, but it doesn't cause any damage either way.

As for the engine operation, try adjusting the mixture control solenoid and TPS. The TPS is really frustrating - I had an '85 Caprice that had one fail and caused all sorts of f'ed up stuff to manifest itself. I discovered that the engine seemed to like a slightly low TPS voltage and a lot of timing advance with good fuel (there is not a very good static compression ratio, so you have to make chamber pressure however you can).

Make sure the O2 signal is good. The mixture control is dependent on the sensor.

Make sure the EGR is operating, and at least sealing. The EGR can keep the chambers cooler for less detonation and preignition.

You might even try a little water injection or top engine cleaner to knock the carbon out of the chambers since your backfire could be from hot spots and/or lean operation and the heat that goes with it.

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Later,
Vader
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"What a Day..."
Adobe Acrobat Reader

 

I'll have to read up on the TPS and mixture control stuff.

As for the O2, it's fairly new.

I'm gonna do the water injection when I get the chance.

As for the EGR, it's long gone, I had it blocked off on the old intake, the edelbrock is blocked off as well.

 

I suppose it's time to buy a DVOM..

 

BTW, the carb and the sensors and whatnot attached to it came off Pony Killers LG4 Z, it ran like an ANIMAL on his car. I adjusted the mixture screws and air valve spring per his instructions.

 

BTTT

 

Would a clogged cat help cause those symptoms?

 

yeah a clogged cat could cause a weird run pattern- it would probably cause a bog etc...


time for high flow cats maybe??

Steve

 

Im gonna Second what Vadr said, as to the Bog being possibly related to the TPS.


When Mine went pooty... It cause all sorta weird problems.


try unplugging it and see if the car runs better, You will run in full PE mode, but it should take care of the bog.. just use it as a test measure, not a fix



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60 Ranchero - Project ( Money Hole )
85 Sport Coupe LG4 - Daily Driver

Just another Hot Rod kid, or thats what they all tell me.
Livin' the Stereotype

 

I might sound ignorant, but I was always told that the TPS on carb'd cars was only for cutting out AC function at WOT. I'd say pull the valve covers and make shure all the rockers are tight, cause that could be the cause of poor performance. That and the Caprice being a very hefty boat.

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'86 G-body Cutlass
Olds 307/TH350
Soon to be 377/700R4
To Beer or, not to Beer...

 

I set the timing at 6-8* which is close enough to stock.

It knocks once at idle now, then VERY slowly takes off. This is from a dead stop BTW.

I'm not sure if I got rid of the backfiring yet, I just took a quick drive to test the new timing, but it backfired on my way home from work, and didn't 10 minutes later when I reset the timing.

It's still idleing at 1000 RPM.

When you floor it from a roll, it pulls real good, the engine sound from the carb is really loud, like WHOOOOOOMMMMMM, real loud, but I'm not sure if that's normal or not..

 

If you gained an extra two quarts of oil wouldnt that tell you it was filling up with gas??

 

Try Unplugging the TPS mac

Sounds identical To what my LG4 did.




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60 Ranchero - Project ( Money Hole )
85 Sport Coupe LG4 - Daily Driver
Reader's ride -> [URL=https://www.thirdgen.org/rides/index.tgo?action=view&rideid=1221 [/URL]

Just another Hot Rod kid, or thats what they all tell me.
Livin' the Stereotype

 

Hell mine sounds like a monster turbo at wide open throttle, but the filter top i got and the cowl induction hood dont help that none- the intake on my car is almost louder than my exhaust!

Steve

 

Yup, it's still backfiring, pretty bad.

Only when the car is cold, and only under a load.

 

I fixed the bog, re-adusted the secondary air-valve.

It still diesels when the motor is fully warmed up.

It still backfires RAPIDLY when slightly warmed up, but not when cold. When it's fully warmed up, from a dead stop, it'll run through first fine, and backfire when it shifts into second. When it's fully warmed up, going uphill, it will backfire occasionally, and rapidly.

Unplugging the TPS didn't help anything but the idle.

I've set the timing about 10 different times. 2 degress advanced from the "sweet spot," it knocks, 2 degrees retarded and it revs like it just took a Hendrix-sized downer and booze overdose.


On another note, I finally got an EGR code, I wouldn't even know what EGR valve to get to put on the performer, so it's blocked off.

I have 17" vaccum at idle, and about 25" at around 1500 RPM.

I can't check the fuel pressure cause I can't find the "T" fitting for my guage.

I don't have a dwell meter.

I did the water injection thing, no carbon from the tailpipe at all, just steam. I'm gonna try it again.

I dunno, this is really pissing me off now..

I'm gonna gut the cat and pull the valve covers to check for a broken spring or whatever, but I can't do that till Monday.

 

Back up top...

 

Mac, 1/8 NPT is the T fitting you need. Try ACE.


What is your Idle set at ? RPM wise.


High Idle, Or a Rich Idle condition can Help cause deiseling.


So can Carbon Hotspots Tho, And thats hard to Rule out.


When you say removing the TPS helped Idle, You mean helped it How ?>

I know this is *******, But try unplugging the MC solenoid ( the blue one )

That will put you in PE mode All the Time.


It sorta sounds like you are running Lean, with all the Backfirng and such.

Might make sense, when cold your choked, So less air, So no lean condition, No backfires.

When You warm up, Choke opens and Hello backfires.


if only 4* up from total Dog Is making you ping, It leads me to belive in a lean condition as well.


How's that O2 sensor ? Ive heard they are fairly susceptable to getting fuxed, So maybe in the swap it got damaged.

Deconning the MCS will take that all out of the loop. Your milage will suck and you will be washing your motor with gas, But its only a experimental measure, I wouldnt drive it around like that

Hope that Helps.



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60 Ranchero - Project ( Money Hole )
85 Sport Coupe LG4 - Daily Driver
Reader's ride -> My Ride

Just another Hot Rod kid, or thats what they all tell me.
Livin' the Stereotype

 

BTT

 

does the mark hold still with a timing light on it, i'm thinking maybe the chain and gear is worn. best to make sure you have a good tune up and do compression check then start trouble shooting.

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ICON Motorsports

1st & 3rd
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