316 struggling to rev over 4k

[bobbin1982]

Not long had my new E30 and i noticed it wont rev very well after 4k revs... is this normal?..... I used to have a 2.5 so this is a new engine size for me

I thought it may be the dizzy and rotor arm?

Its a 1993 316 touring

[darkchild]

It's normal for M40s with knackered cams, usually caused by a blocked oil spray bar.

[bobbin1982]

Bloody hell!....... Not what i wanted to hear...
Had the car 2 days and this already



Suppose im going to have to buy a donor engine...2.5 i suppose


Thanks , Andy

[Yeti]

yea the cams are shite lol

[bobbin1982]

Ok update on this

It isnt always 4k revs... The car revved over 4k fine when i took it out earlier

Its under load at most rev ranges... Also its not a smooth engine noise but a spluttery one as in very lumpy...Is it maybe as i suggested Dizzy and rotor?

Or is it the dreaded cams for definate?

Thanks , Andy

[Brianmoooore]

Poor ignition components can cause a severe misfire at high revs. 0n the M40 engine, which can act very much like a rev. limiter. Makes a sound similar to the old F1 engines when traction control kicked in, if you can remember that.

[bobbin1982]

No i cant remember that
Yeah its like a constant misfire under load or not even

Just want to try and get the car right if i can before swapping engines

So would you recommend me trying new dizzy rotor and plugs maybe to start with?

[Brianmoooore]

At least take the distributor cap off and inspect it, and whip the plugs out while you're at it.

[bobbin1982]

well i suppose thats the first call!!

Cheers ill report back with my new found wisdom shortly

[bobbin1982]

Ok i found out that there is only 2 out of 3 bolts holding the dizzy cap on
And when i took the rotor arm off i offered it up to roughly centre of the cap and there was 1.5 to 2mm gap between the rotor metal and the dizzy metal (Arent they supposed to touch?)

I took all leads off one by one while engine was running and the engine struggled with every lead off so i assume the leads are ok


Have i helped diagnosis in any way?

[bobbin1982]

Did not take the plugs out as i have misplaced my plug socket!!

[bobbin1982]

assumed the dizzy and rotor were pretty knackered so orded them fro ECP this afternoon

[bobbin1982]

Well!!! Loads better than before but still a little lumpy

Changed the dizzy, rotor and plugs.... One of the leads has a split in would this make a huge difference?....

Also want to check if the leads are in the right places... does anyone have or know of a picture that could help me?


Thanks, Andy

[Brianmoooore]

A 4 pot would be more than a little lumpy with two leads swapped over.
Can you see any markings on the leads? OE leads don't normally fail, but someone may have fitted aftermarket ones somewhere along the way.
Looking at the ignition system in pitch darkness with the engine running can sometimes be instructive.
Lumpy at idle, or when at 5000+ RPM?

[bobbin1982]

ill wait for this evening and find somewhere dark like the woods!!

Its mainly at higher revs say 3500+
Otherwise its driving alright... the hesitation has stopped while pulling away etc so new rotor and dizzy has helped somewhat

Just checked for markings on the leads and they are just made by bremi as i can see.. not sure if they are origional... they do look fairly old though

[bobbin1982]

Update... it isnt happening all the time... I ran the car tonight and ran it all the way through 2nd 3rd and 4th with no hiccup... then as i got through the city i ran it hard again and it was hiccuping again...

It seems its not a constant thing!

[bobbin1982]

maybe crank sensor?

[Yeti]

fuel pump

[bobbin1982]

Really?... Have you had a similar problem?
I used to have a 325 touring and went through 3 secondhand pumps but when they were on the way out it just shut off the fuel completely and the car stopped
I them had to get out and lift the seat to bang the top of the pump cover and 9/10 times the car would fire up again for a week or 2

[bobbin1982]

Ok just checked for breaks in the leads as suggested by brian and two of the leads are lighting up orange when wiggled
The lead from the coil and the lead from no 3 cylinder

So new leads are needed

[bobbin1982]

All the parts i have replaced are pretty much regarded as service parts so far... makes me wonder when the last filter and oil change was done!

[bobbin1982]

today i fitted new leads and put some super unleaded in and some redex

Seems to have helped quite a bit...

Also cleaned the engine as it was manky while i was at it too

Its happening loads less now and it seems a lot smoother to drive... so i think maybe the cps was dirty and i cleaned it when i done the engine bay or the redex and super helped the fuel filter and injectors and what have you maybe?....

Or even as yeti said the fuel pump is on the way out and cant keep up at higher revs all the time?


Thanks, Andy

[Brianmoooore]

Looks like your car has multiple faults, and you are making progress.
Leads might have helped, but the Redex and super unleaded will only have lightened your wallet.
I don't go along with the fuel pump theory. if the pump can supply enough fuel to feed the engine at low revs under load, it can easily supply enough for the engine to rev to the limiter under no load.
E30 pumps normally fail in one of two ways - either the commutator of the motor starts to wear completely away, leading to the motor failing to start when the motor happens to stop previously with a carbon brush on a worn patch, or wear occurs in the pump gears, resulting in them jamming up, when again the pump will fail to start. In both cases, when it's running, its output is near enough up to what it should be.
If you're not convinced, then buy a cheap (£20) ebay fuel pressure gauge, and check.

[bobbin1982]

Always thought redex was a gimmick anyway... just trying to try things to see the outcome...
I might get a new cps and fuel filter possibly... i just dont get it... it seems like an electrical fault of some sorts really
I cant see the coil being bad as there is nothing to go wrong in them from my experience


I eventually want to get a m42 b18 as you said in another post brian but i would like to get this sorted somewhat so i can enjoy the car while i source what i need

Its loads better but i havnt quite hit the spot

[bobbin1982]

While im chucking money at this underpowered lump i lose money on the new lump

[bobbin1982]

found a split breather hose from the rocker cover!... Gonna check the rest and order as needed..
Also gonna clean throttle body as this seems to more dirty than my mistress

[bobbin1982]

Just done a bit of reading and it sounds like my hydraulic lifters and/or cam are knackered as I have a loud tapping noise

So onto the search for a m52 b18 as Brian suggested


Andy

[Brianmoooore]

There's a world of difference between a knackered cam and knackered hydraulic tappets. The cam is serious news, but the tappets just cause a noise and have little effect on performance.
It's unusual for tappets to knock all of the time - usually it's just when the oil is cold and/or at idle.

[bobbin1982]

It's a tap most of the time really
It's annoying as I haven't had the car long
The body is clean as a whistle apart from the odd scab on the doors or boot
I'll check harder tomorrow

[bobbin1982]

Drove to kent from Norfolk yestersday and the engine was happy enough at around 70/75Mph but wouldnt drive over 80... It felt as though it was firing on 3 cylinders then when i let off the gas and lowered the revs to around 3.5k it took about 30 seconds to act normal again
When it does return to what i assume is normal its like its magically disappeared

Acouple of times in 2nd and 3rd gears it just went all the way through and like there was no stopping it

I know its a 1.6 but this is silly

I have replaced:

Ht leads
Rotor
Dizzy
A breather hose from the rocker cover to throttle body

Maybe it could be a fuel starvation or its firing incorrectly most of the time?
I really want to get to the bottom of this as its irritating


Thankyou very much, Andy

[bobbin1982]

Can i do anything to the airflow meter of adjust the ration maybe?