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The mkiv Supra Owners Club

Lack of power - NA


Homer
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No jokes please :D

 

My NA seems to be lacking power, just had a fellow NA owner take it out who confirmed..

 

There's no misfire noticable and everything seems to be working, is there anything obvious to check considering there doesn't seem to be an ignition issue?

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Check to see if the Turbo's are missing.... If they are, it's an NA and perfectly normal :D

 

On a serious note I guess things to check could be, Fuel Filter, FPR, spark plug gap...? Not too up on the NA but those are the things I would look at on any other engine so I guess it would apply. The NA has a distributor based ignition doesn't it? Have you checked dizzy cap, rotor arm etc, I know you said there were no misfires and the ignition was fine, but worth checking if you haven't already? Is it decatted?

 

Once you've checked the obvious, maybe a compression test is in order? I'm no mechanic though, so my opinion might not be worth much ;)

Hope you get it sorted :)

Edited by kill1308 (see edit history)
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put a sock over the air filter and rev the nuts off of it while spraying some of that cleaner fluid stuff in. will smoke round the back but will clean it up a lil.

 

also you guys may laugh but a mates car was running lumpy and turned out there was a dead squirrel in the exhaust but this was pretty noticeable because the car just went so quiet!

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Your having the same symptoms I had with my supra being parked for so long, and I also did with my clutch. Iv been using the lique moly stuff and driving it more. The cars started to pick up more power, i reckon being parked for 7 years my valves were sticking etc as I did have low compression

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mines like this at the moment ive done

 

spark plugs

oil filter and oil

o2 sensors

took intake manifold of cleaned inside

cleaned apexi air filter

checked exhaust manifold gaskets ect and for damage

reset ecu still on v power

checked tyre pressures as rears were a little down

change vac pipes

 

last time my car felt sluggish it was a caliper sticking this time its not lol so im trying to locate the source...... fuel filters next to be changed

 

also as a comparison my bros 1.6 vtec civic can keep up till 3rd gear which is stupid as before it would be behind by half of first gear

 

he finds it funny though im due at the garage to have compression ect checked just incase as at the mo it just has no go

 

I will be checking timing as scott says as on my bros civic it managed to jump and mess the timing up and his car was similar

 

on a private road of course it managed 6200rpm in 5th gear quite easily so not quite sure whats going on

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also as a comparison my bros 1.6 vtec civic can keep up till 3rd gear which is stupid as before it would be behind by half of first gear

 

So you fancy that race now ;)

 

When i first picked up my car it had been stood for quite a while and felt very 'restricted' even after a service it didnt feel much better. i Had a good few days of giving it hell through the gears and it seems to have cleared it up. Anytime it feels like its driving poo i give it a clear out blast and it seems to work, looks like a few others get similar problems to me.

 

Checked all earthing points?

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actually a little side by side action might be a good idea let me know how much the car is actually down by :eyebrows:

 

also had a play with the 2nd butterfly in the manifold cable tied it in open position then in closed position

 

in closed mode when it gets to its usual switching time boy is it slow like it just gives up also it seems to me that either way changes the exhaust note which seemed cool ha

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Thanks for all the feedback guys, some good pointers there and gives me some ideas to work on :)

 

Just to try and rule out a few:

 

- Rob drove my car immediately after driving his own one (and I've also driven his NA quite a few times). There is a very noticable difference between the two and you'll just have to trust me that it's not exhaust noise making the difference. It feels like it's got 60-70% of the power of his one

- Power is down equally across the rpm range.

- The 2nd butterfly in the intake appears to be working as there is the normal noticable pickup in power around 4.5k RPM

- Car has not been serviced recently however the fuel filter and air filter are new

- Petrol is fresh, it was empty initially and has had two complete fill ups since the MOT last month

- Rotor and dizzy are like new, along with the leads. There's no sign of misfire, so could it really be a weak spark?

 

 

Question on the buttery valve - are there one or two of them in the intake?

 

Suspect items from what you've mentioned:

- blocked exhaust? The 1st cat has not been off and had a hard knock when we removed the engine a couple of years ago - maybe one cat is blocked/damaged? There is a small leak on one of the joins so may be highlighting a problem with back pressure on the 1st branch...

- Fuel pump? Pulled from a box in Jez's yard so maybe on it's way out or just past it's useful life

- Spark plugs - looked new but have not replaced. They are probably 3 years old, but have liekly done less than 1k miles

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A blockage in the cat could cause a loss in power due to a buildup of backpressure I'd have thought.... another thing worth investigating I'd say if you've explored most of the other options now. If you're mates got an NA you could always try his exhaust :D

 

Are you definitely sure it's not ignition related?

 

Hopefully someone who knows what they are talking about will be along shortly though :D

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