Trying to run previously carb'd 1.8 on FI Options

[aarch]

I got a free 1.8 engine (EC005197) that had previously been set up with carbs. All I got was the engine, no FI or carbs. I have a '72 1.7 with the original engine and FI. I swapped out the engine and put the entire original 1.7 fuel system (FI, computer, throttle) onto the 1.8. Where the original 1.7 was anemic at best, the 'new' 1.8 was much, much stronger. It pulled far stronger, revved faster, and under any throttle it ran perfectly smooth. I've never dyno'd either, but it felt like ~20hp increase. However, under neutral throttle, at cruising speed the power output would stutter/hesitate. It didn't misfire, sound rough, or cutout; it just wouldn't maintain a steady speed.

At the time I thought it might be a vacuum problem, but I'm wondering if it was a cam issue. Did all that extra power come from a high performance, carb-tuned cam that won't work with the FI? Or is it an incompatibility with the 1.8 engine and the D FI from the 1.7? I ended up putting the original engine back in it. It's a shame to have that beast of a 1.8 just sitting in the basement though. Any thoughts would be much appreciated.

Thanks,
Andy

[Dave_Darling]

Probably cam related. The 1.8 was rather lower compression than the 1.7, and actually made less power. (76 HP DIN vs. 80 HP DIN spec.)

--DD

[Spoke]

Or is it an incompatibility with the 1.8 engine and the D FI from the 1.7?

I'm running DJET from a '71 1.7L on a 1.8L with no problems. Runs like a champ.

[jimkelly]

from what I've read here, even if an engine has carbs, there is a low percentage chance that the engine itself has a carb cam in it. I wonder if there is a way to turn the engine with plugs out and watch the rocker action to determine if engine actually has a carb cam in it???

all the best.

[Tbrown4x4]

You need a degree wheel, a dial indicator and the cam specs. Then you basically map the lift and duration and compare it to the cam specs.

I'm not too familiar with VW/Porsche engines, but if you pull the oil pump, is there any ID marks on the end of the cam?

[SirAndy]

I'm running DJET from a '71 1.7L on a 1.8L with no problems. Runs like a champ.

(IMG:style_emoticons/default/agree.gif)

I ran a 1.7L D-Jet on a 1.8L block with no problems.

Might be a carbed cam in the 1.8L block ...
(IMG:style_emoticons/default/idea.gif)

[rhodyguy]

Could even be a 1911. No telling. But if it was rebuilt and "setup" for carbs you might consider a loaner or rental set to see how it works. You're into the engine at the right price. Throw a little money at it. Would a struggling MPS cause the stutter/hesitation?