Reluctant To Rev Past 5.5k

[dommorton 0]

I've just finished fitting weber 45's to my 1.9 8 valve.

 

I didn't really expect it to run 100% without a tune but it does go rather well (don't worry it will be getting checked out). However it still has an issue that was present when the car was on standard injection

 

In first and second it will pull strongly to the red line. However in 3rd it really doesn't like reving over 5.5k. It will if pushed but it's like you've hit a wall and it climbs very slowly and doesn't feel right.

 

Fitted new plug leads today when I finished off fitting the carbs.

 

Any suggestions what may be holding the old girl back?

 

I wondered if the exhaust may be blocked?

Edited May 4, 2008 by dommorton

[westy 0]

Have you tried swapping the ignition amp for a known good one?

[dommorton 0]

Nope

 

Are these the symptoms of a duff amp then?

[McDude 33]

That's where I would have looked first.

Get an OE one if you do swap it out, the cheaper ones are pants.

[Rom 0]

Amps can cause all sorts of problems.

 

That would be my first port of call also

[dommorton 0]

Cool thanks I'll check it out

[dommorton 0]

Right I've tried another Amp and it's exactly the same. Also swapped out the Tach Relay and no change.

 

However we whipped the plugs out and they are black as hell. Guessing the carbs need setting up then we need to see if a problem is still evident.

 

If so I guess the next stops are the cam timing and the exhaust as there isn't much left to check.

[welshpug 1,626]

ignition timing can also have an effect, also if you alter cam timing the ignition will need to be checked again.

[dommorton 0]

Changed the rotor and cap now too as the rotor looked a little iffy.

 

Leaned the mixture out and now have clean plugs.

 

Played with the timing and fuel pressure no change.

 

Still no dice over 5.5k in 3rd and 4th

 

Goes really well until then tho Confused almost feels like there is a rev limiter on it.

[mfield 20]

As random as it sounds i once had a problem with an alternator not giving out enough power higher in the rev range, felt like i was hitting a limiter as well. Changed it over and all was fine, it was also more evident in the higher gears.

[westy 0]

Just a thought, your carbs could need setting up properly, maybe in the higher revs they're not supplying enough fuel?

[Daz_C 8 1 Cars]

I know you've only just put them on so have you put the filters on ? I had a similar issue with mine and it turned out to be that there was too much air getting into the carbs at higher speeds (possibly icing ? or whatever its called) ....... then I fitted my filters which cured the problem.

[dommorton 0]

As random as it sounds i once had a problem with an alternator not giving out enough power higher in the rev range, felt like i was hitting a limiter as well. Changed it over and all was fine, it was also more evident in the higher gears.

 

Blimey that is a curve ball! lol

 

Sounds plausible tho.

 

The alt on the car is a 2 year old refurb item I fitted myself.

 

Guess I need to check the output from it to see if it's ok.

 

Thanks for the info.

Edited May 13, 2008 by dommorton

[dommorton 0]

I know you've only just put them on so have you put the filters on ? I had a similar issue with mine and it turned out to be that there was too much air getting into the carbs at higher speeds (possibly icing ? or whatever its called) ....... then I fitted my filters which cured the problem.

 

 

Yes I have fitted some filters.

 

I appreciate the carbs could do with setting up for my car however they came off a 1.9 and I have checked the jet sizes. I'm just hung up on the fact I had the issue on injection too.

[Anthony 1,000]

A dying coil can give these issues as well - especially seeing as that's common between injection and carb. Usually worse under full load than on part-throttle in my experience if it's the coil.

[Henry 1.9GTi 36]

surely a standard 8v feels a bit strained up at 5.5k anyway? I know mine did and its more noticiable in higher gears just because it takes longer to rev, will it pull to 6k or not atall? sorry not very constructive perhaps my 8v had a simliar problem without me knowing.

Edited May 14, 2008 by Henry 1.9GTi

[dommorton 0]

Standing still it'll rev freely to just under 7 (that's as far as I took it as no limiter) without feeling in any way strained.

 

However under load on the move it just stops reving and sounds awful at 5.5k

 

I have a Magnex system to fit on it so will see if that makes any difference.

 

Otherwise I will try another coil as it's one of the only ignition components left to change out.

[Henry 1.9GTi 36]

Is the magnex including downpipe/manifold? Could have a mangled spliter in the down pipe, always worth a look as its only 2 bolts.

 

Hope you managed to get it sorted.

 

Henry.

Edited May 14, 2008 by Henry 1.9GTi

[dommorton 0]

Is the magnex including downpipe/manifold? Could have a mangled spliter in the down pipe, always worth a look as its only 2 bolts.

 

Hope you managed to get it sorted.

 

Henry.

 

The Magnex doesn't include the manifold unfortunately.

 

However I'm taking the downpipe off and fitting a new mounting kit to it so will check the inner while I'm there

[drmo 5]

Have u tried to drive it to 3rd easy and then step on the throttle? It sounds like u flor it every time from first to third gear, that means that maybe they run out of fuel. Is there any backfire from them?

 

Also it could be the problem that the main venturis are too small.

Edited June 2, 2008 by drmo

[westy 0]

Standing still it'll rev freely to just under 7 (that's as far as I took it as no limiter) without feeling in any way strained.

 

However under load on the move it just stops reving and sounds awful at 5.5k

 

I have a Magnex system to fit on it so will see if that makes any difference.

 

Otherwise I will try another coil as it's one of the only ignition components left to change out.

 

By 'sounds awful' - do you mean it sounds like its misfiring?

[woodsy 0]

This may be worth checking as it happened on my carbs.Remove air filter and check that the venturis are not loose inside as they are held in with screws that vibrate loose.Mine did and they where brand new and i put some lockwire through the screws as one had come out completely.Worth a look.

[dommorton 0]

It sounds like it's hitting a rev limiter but doesn't feel like a misfire.

 

Hard to explain but you can tell you've reached the limit.

 

The other day it flew to 6.5k and went like stink. Then I tried again and 5.5 limit

 

I've another coil to try and will check the venturi's aren't loose as suggested.

 

Have checked specs of all the jets and the chokes and all check in with those required for the engine size.

 

Fuel pressure is maintained at a steady 3.5PSI and doesn't change with revs.