Sudden improvement in power with no work done.... (1 Viewer)

[crave reFleXion]

Freshly rebuilt 14BT (including pump and injectors) about 20,000km ago. I've felt that I've had a bit of fuel starvation for a while, especially at higher revs when giving it a bit, and then all of a sudden I've got a noticeable improvement throughout the rev range including up high 2.5 to 3k. More get up and go ... Now, I'm not complaining, but I'd like to understand what might be going on.

Any ideas?

 

[KamarulF]

Any changes in motor oil? Fuel filter?

 

[traveldud]

Consider air filter too if recently replaced...

 

[crave reFleXion]

Any changes in motor oil? Fuel filter?

Absolutely nothing at all... The only thing I can put it down to is going for a 3 hour drive on the highway. But I had also gone for other long drives since I noticed it was lacking a bit of power, but it hadn't changed anything like this.

 

[KamarulF]

Perhaps all the deposits got cleared out from the exhaust during your drive

 

[GTSSportCoupe]

Maybe something was partially clogging the fuel pick-up in the tank and it moved?

Does that motor have a rotary injection pump? Maybe something has changed with the boost compensation? Fuel pin wasn't moving and is now?

Brakes were dragging and now they're not? You added more air to your tires?

Haha, just ideas. But in any case, your rig looks fantastic.

 

[crave reFleXion]

Thanks mate... Yeah, it's got me stumped. Feels a lot more responsive like it's getting more fuel. Yeah, it's a rotary IP. Trouble is I've been tracking my fuel usage and doing some acceleration testing to find a sweet spot for IP timing, but a random improvement like this when nothing has changed will throw a spanner in the works.

 

[AussieHJCruza]

Did you 'clear the cobwebs' out of it?

My guess is that there was some crud in fuel line or pickup somewhere that has dislodged and now she's not starving for fuel

 

[roscoFJ73]

When I had a 1HZ rebuilt it took maybe 10000klms to loosen up. But it was gradual.
Were you getting any heat from the engine?
Some kind of fuel starvation is my best guess. If it was an air obstruction you would have black smoke. Did your throttle linkages move in some way giving you more top end?

 

[lowenbrau]

Diesel algae in the tank perhaps? Might have just been a bit that finally worked its way through a screen somewhere. Wouldn't hurt to run some biobor though any diesel system that has been in storage.

 

[mudgudgeon]

Have you been adjusting the pump timing?

What makes you say it's been starving for fuel?

I think a partial fuel blockage that has finally cleared makes sense too, without more information

 

[crave reFleXion]

Did you 'clear the cobwebs' out of it?

My guess is that there was some crud in fuel line or pickup somewhere that has dislodged and now she's not starving for fuel

I reckon you could be right. I reinstated an internal long range fuel tank (110 litres) a while ago which hadn't been used in ages and it took a bit of cleaning. I've since put probably 5 or 6 more tanks through using my usual rear main tank, which is clean. I've got seperate Ryco fuel filters pre electric fuel pump and another just before the IP in the engine bay, and I noticed the pre filter for the internal long range tank has some diesel growth. I did put some biocide into both tanks a while ago, but I might keep the treatment going a bit longer. Actually, I might drain the dregs in the internal tank before I fill it up again.

I might also change all of the fuel filters again. Any other ideas/advice so I don't put more crap through?

 

[crave reFleXion]

Have you been adjusting the pump timing?

Yes, unfortunately an FSM for a 14BT doesn't exist, so I'm in the process of testing to find the best timing.

 

[GTSSportCoupe]

Yes, unfortunately an FSM for a 14BT doesn't exist, so I'm in the process of testing to find the best timing.

Have you downloaded this one that covers the 1995 14B, 15BF and 15BFT? It must have a lot of info that crosses over? They all have rotary pumps?

 

[crave reFleXion]

Have you downloaded this one that covers the 1995 14B, 15BF and 15BFT? It must have a lot of info that crosses over? They all have rotary pumps?

Yeah, but the timing specs for factory turbo and na diesels is always different and I can't find a pattern. Some turbo versions have more retarded timing (15bft for example) while others are advanced (1hdft). Pain in the arse really.

 

[GTSSportCoupe]

Yeah, but the timing specs for factory turbo and na diesels is always different and I can't find a pattern. Some turbo versions have more retarded timing (15bft for example) while others are advanced (1hdft). Pain in the arse really.

Probably has to do with cam plate differences. If some have more lift (give more plunger stroke) it'll throw all the specs. I'm no expert, but I think the turbo motors get a more aggressive cam plate.

 

[crave reFleXion]

Probably has to do with cam plate differences. If some have more lift (give more plunger stroke) it'll throw all the specs. I'm no expert, but I think the turbo motors get a more aggressive cam plate.

Yeah, I'm definitely no expert either... I'm just doing some time trials and following fuel economy figures to find the right balance.