help

[tazzjazz]

hi guys can any1 help,having trouble with my 98fc none turbo,it won,t rev past 4000revs under load,ive changed the ecu still the same,any advice would be great

[m1tch]

Hi there and welcome in

It won\'t be a 98 as the FC stopped being made in 91, can you give us some specs of the car and engine and any modifications, it might be something as simple as electrical leads the wrong way round or timing being out.

[tazzjazz]

sorry i meant 88,its pretty much standard apart from the exhaust,it was running fine till i had my exhaust welded,the battery was not diconnected,thats why i thought i spiked the ecu,i changed that but its still the same.its a gen 2 1988 none turbo

[L18M]

exhaust welded? as in patched a hole or changed the exhaust if you changed the exhaust then maybe sth to do with the o2 sensor? or lack of?

[tazzjazz]

changed the exhaust,theirs never been an o2 sensor on it,as far as i no it came with a custom manifold and no cat,the manifold goes straight through to the y piece

[TiddlesRX7]

There should be an O2 sensor in the down pipe.

[tazzjazz]

i,ll av a look 2moz,it will go past 4000revs in the drive,but as soon as its on the road its like hitting a wall it just won,t drive through it

[m1tch]

Im guessing this is when its up to temperature right? what fuel pump does it have? When were the plugs/HT leads changed?

[TiddlesRX7]

Or it could be getting un-metered air into the engine perhaps. Check the intake pipes after the air flow meter for cracks and nip up the clips.

[tazzjazz]

yes when warmed up,ive got newish 10mm leads,not sure when plugs were changed,i,ll try the intake pipes,thanks

[m1tch]

4k rpm or so is when the primary and secondary injectors swap over/come online, it won\'t happen unless its under load, so check for air leaks, but it might be a fueling issue.

[tazzjazz]

what makes the secondry injectors kick in

[grinder]

not sure if the egi is the same - but its around the 3800 rpm mark

and you get hesitation as they swap over

usually down to a bad earth or so im lead to belive

have a look on rx7club.com for the 3800 hesitation - there is loads of info on there

[m1tch]

what makes the secondry injectors kick in

The primary injectors increase the duty cycle up until a point, usually about 4k rpm or so, then the primaries reduce back a bit and the secondaries fire fuel in as well. The ECU will decide on how much fuel is needed, so when reving it on the drive there is no load on the engine, so not as much fuel is needed, wheras on the road it will be under load so extra fuel will be needed.

Might be best to check all the air hoses first though, as the OEM air intake hose is notorious for splitting.

Does the car idle ok or is it quite lumpy?

[tazzjazz]

no it idles good,really smooth,starts spot on,runs great upto 4k,then as i say won,t go through it like hitting a speed limiter