Lugging at Higher RPMs

[blueguitar322]

2000 EX, manual transmission, i4 engine...previous owner installed 4-2-1 headers and a cold air intake.

A check engine light came on and the engine shuddered to a stop (and wouldn't restart) last week. I took it to a shop where they read the codes and fixed the problem (some seals near the timing belt started leaking oil)...except something is now different.

I used to be able to cruise around town in 5th gear at 45 mph and 1800rpm or so...often I would set the cruise control to prevent lead foot syndrome and the engine wouldn't have any issue accelerating at that gear/rpm, e.g. going up hills.

In fact, I could short-shift and floor the gas in 5th gear at 1200rpm and had no issues. It wouldn't accelerate too fast, but no weird behavior.

Now, anytime I'm below 2000rpm and try to accelerate (3rd/4th/5th gears), the engine starts to lug. It never did this before. I took it back to the mechanic and they told me smaller engines prefer higher rpm (i.e. above 2000) and that I shouldn't shift until about 3000 rpm. I asked them about gas efficiency and they said keeping rpm's higher would actually help, not hurt.

Now obviously I can change my driving style, but it's a bit disconcerting that I didn't notice this behavior for 2+ years of owning the car, and it's there now and considered normal.

What do you guys think? When does the engine start to lug for you?

 

[ryan s]

my buddy does the 1-2-5 shift (even at 30mph) and it drives me bat**** crazy that is one of the myths of improved MPGs...that lower revs = better mileage. without getting technical, the throttle plate is basically closed at such low revs so the car is basically "gulping" for air.

as for the "lugging" does it just sit while the revs get higher, or does the engine actually feel like it lost power?

 

[blueguitar322]

as for the "lugging" does it just sit while the revs get higher, or does the engine actually feel like it lost power?

Modulated power loss, plus a back-and-forth shudder that is very obvious. Eventually, when the RPMs climb north of 2000, that effect dies down.

You know how, if you're crawling along in first and brake to come to a complete stop but don't ever disengage the transmission by pushing in the clutch, the engine will start to violently shutter before dying? It's that same action...or at least the beginnings of it.

I've always called it lugging the engine, but perhaps there's a better term.

 

[HondaLuver83]

Its like riding a bicyle up a hill in the very last gear, no matter how hard u try, u aint gonna go very far or fast.

 

[blueguitar322]

Its like riding a bicyle up a hill in the very last gear, no matter how hard u try, u aint gonna go very far or fast.

Before the breakdown/repair, the engine wouldn't shudder under slight acceleration at 5th gear / 45mph / 1800rpm (e.g. the type of acceleration that would take me 45-50mph in 4-5 seconds. Slight.). Now it does. The car physically shakes.

The only way to avoid that is to never push down the gas pedal unless (1) i'm in 1st gear or (2) I'm above 2k RPM.

It's easy for me to accept that accelerating at lower RPMs isn't the most effective way to drive. But why would there be that dramatic change in engine behavior? That's what I'm trying to understand.

 

[ryan s]

ohhhh that type of shuddering...same thing that happens when my buddy will slow down for a car turning then leave it in 5th and try to accelerate from like 10mph

did they have to mess with an engine mount to get to the seals? could be a vibration caused by that, since everything has a resonant point...

 

[blueguitar322]

Just an update in case anyone else comes searching with a similar problem in the future.

As part of the work that had been done on the engine previous to this issue, the distributor & wires had been replaced. One of those parts was defective and causing misfires.

I probably threw everyone off by using the word "lugging" when I should have left it as a more general "strong engine vibration". Turns out it didn't really have anything to do with lugging the engine. The mechanic pointed out that the vibrations weren't rhythmic, thus it wasn't a timing belt or motor mount issue either.

Replacing the distributor and wires (which they did free of charge as the parts were defective) fixed the issue. Back up and running without any vibration and engine is operating as expected at all RPMs.