Exhaust Manifold Swap

[Can1991Ram]

Tonight I finally swapped the cracked exhaust manifold for one from my 88 2.0 parts engine. I welded up the egr tube and the oxygen sensor fit just like on the 2.4.

This is what the old manifold looked like on the inside.

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White in the number 3 tube

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VERY white where the manifold meets the exhaust pipe.

Is this oil that causes this?

[geezer101]

I would think it'd be black if it was oil. I'd say it was running lean on #3 cylinder (dud injector or an air leak somewhere? )

[Can1991Ram]

I'm wondering about that too.. someone said ethanol blending fuel can do this.. but then all the cylinders would look like that.

[geezer101]

Time to get your Scooby Doo on and solve the big mystery The lean out could be the cause of the manifold crack too...

[Can1991Ram]

well.. between the coil swap and exhaust manifold swap, the over 4000 rpm is a bit better. At about 4700 it now basically stops pulling ( I know it's not a drag car.. but passing someone would be nice). Before it was all done around 4400rpm. I'm gonna say the coil swap has helped a ton.

I'm gonna play with the ignition to see if I can find anything. I get 16 in of vacuum at idle (which isn't bad) and I'm gonna see if there is anything else there for improvements with adjusting the timing. If not.. it will have to wait for the head swap to see any improvement.

[Can1991Ram]

Well.. I think whoever changed the belt got something wrong. I turn ed it to full advance and got 20 inches of vacuum. Of course.. that is too much.. so I backed it down until I got 18 in of vacuum.

I think the belt must be off a tooth.

I would be curious to see the timing on a light but I don't have one.

Yes.. I did ground the brown wire before I did this.

[geezer101]

Hmm, something ain't right that's for sure. You need to know what the base timing is like before you can experiment with tuning.

[Can1991Ram]

Well... this is interesting...

I pulled 2 litres of water through the vacuum tube on the back of the intake.... TONS of steam...

After a few hundred kilometers of driving the truck really started running better... mileage was a bit better... but not much else changed. It started and idles better and is a little snappier on the bottom end.

I ran a container of gum fuel injector cleaner through a half a tank of fuel. Added fuel today after running it through.

Now this morning... the truck ran normal. 6 inches of vacuum in OD at 50 mph.

I got in after work and on my way home I noticed I was able to get 10 to 12 inches of vacuum at 50 mph... a ton less throttle needed to keep the speed.

What the heck would cause such a big change? The weather was exactly the same this morning as after work.

[geezer101]

Possibilities - inaudible detonation from the carbon build up nerfed the engine. Steam vapour cleaning the O2 sensor Fouled injectors. Spark plugs de-carbed from the water. Maybe the valves are seating tighter due to the de-carb and fuel treatment. Now you have restored performance, it would be worth experimenting with ignition tuning and unearth some hidden power.

[Can1991Ram]

The next thing is the 2.0 litre head rebuild, port and polish. I'm done with the current combo. Its tired and old.

I've even thought about ditching the factory FI for a holley sniper set up on a modified 2.0 lite carb intake.

[tortron]

Carbon build up causing pre-ignition
High vac reading can be overly advanced timing. If it's all carboned up itl ignite before it sparks.

Did it run on a bit when turning the key off?

[geezer101]

I've been toying with an idea for a while now but the biggest hurdle was the intake manifold - bike carbs. If I used the lower half of a 2.4 manifold and sculpted it down, then had some 36-40mm ID alloy tube welded into it, it might be viable to adapt a quad carb rack off something like a CBR900RR. They're big stonking carbs that will flow whatever you can squeeze out of them. The throats are 38mm which matches something like the 38DGES Weber carb but being side drafts would have serious throttle response.

[Can1991Ram]

Carbon build up causing pre-ignition
High vac reading can be overly advanced timing. If it's all carboned up itl ignite before it sparks.

Did it run on a bit when turning the key off?

I have never had an issue with Pre-ignition. Just low vaccum driving down the road.

Yesterday in a very strong head wind I had to turn off the OD just to keep at 65 MPH on the highway. It would in OD but I would have to almost floor it to do it.

I really think the engine is extremely warn out. Off the highway in the headwind I could get 8 in of vacuum at 50 mph.

To me that says this engine is WAY down on power as it needs a ton of throttle to make any power.

[geezer101]

You have the symptoms of an air leak somewhere - white carbon build up + low vacuum. You'd need to check everything that is affected by manifold vacuum but a compression test would be advised as well. You never know. If the bores don't have a lip on them and the pistons still have visible machine marks all around the skirts, you could get away with deglazing the bores with a scourer ball and installing standard size rings. I honestly thought the engine in my Lantra wagon was a boat anchor when it started belching black smoke but it's running great after a quick run through with a $5 scourer ball and new NPR standard size piston rings. The most annoying part was the pistons and rods themselves. I sent them off to be cleaned in a shop and they were crappy when I collected them (there was gunk still blocking the gas ports and in the ring grooves and they had a layer of some weird residue on the alloy that turned it a dull grey). Took me 5 hours to strip every trace of carbon from them and polish up the pistons.