Author Topic: revs limited and dies under full throttle...WHY????  (Read 11009 times)

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Offline fintelboss

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revs limited and dies under full throttle...WHY????
« on: Nov 22, 2005, 03:20PM »
Can someone please help me...

Ive just been given my mums 1989 Pintara GLi, and alls good with it EXCEPT when under full throttle, or high revs, (30km/h for 1st, 60 km/h for 2nd 85km/h for 3rd etc) the engine just dies. It doesnt stall, it keeps running when i take about 1 cm off full throttle or change up a gear, but i know that something must be wrong. I had my school auto class take a look when i first got it to change oil and brake and power steering fluid etc. but none of the kids knew what to do about this. it has done 190000km, and i have read the cam belt needs replacing at 200000, so is it something to do with that? please help me!

Offline wombat

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Re: revs limited and dies under full throttle...WHY????
« Reply #1 on: Nov 22, 2005, 03:26PM »
won't be anything to do with the camshaft belt - they're the sort of thing that work fine or not at all.

I reckon it could be a weak spark on one side.


At high revs, one side of spark plugs shut down, and that'll mean that the car'll run like crap if the other side are dodgy.

Check all 8 spark plugs for a good clean spark.
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Offline fintelboss

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Re: revs limited and dies under full throttle...WHY????
« Reply #2 on: Nov 22, 2005, 05:20PM »
i just checked all eight, they all seem ok, but black and sooty around  the edge.

the engine also has an odd vibration, noticable when iddling, is this part part of the problem?

Offline wombat

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Re: revs limited and dies under full throttle...WHY????
« Reply #3 on: Nov 22, 2005, 09:39PM »
black and sooty = car running too rich.

I thought you were doing automotive stuff at school? I never saw under a bonnet until i was 17 - okay, i'm mid 20's now, but still...

I get the odd vibration thing too. I don't know what it is, either.
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Offline fintelboss

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Re: revs limited and dies under full throttle...WHY????
« Reply #4 on: Nov 23, 2005, 08:55AM »
Could bad spark plugs make the engine cut out all together though? it does the exact same thing under full throttle no mater what the revsl, does one side cut out then aswell? Do you think i should get 4 or eight new plugs, and which side if just four, or just scrub them clean? Thanks for your help and sugestions so far.

Offline wombat

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Re: revs limited and dies under full throttle...WHY????
« Reply #5 on: Nov 23, 2005, 11:33AM »
I'm not sure which side run all the time and which side kick in and out.

To check it, unplug the wire from one coil to the distributor. If the engine won't start, that's your primary set of plugs.

When it dies, does it die, and then come back and rev? that's what my car used to do (herein referred to as Old George)

Oh, and by the way, not many people know about the spark plugs on Pintaras - when each side fire and don't. I'm going to one day rig up lights or 2 tachos and see which spark plugs fire.

One bank definitely cut out at high revs (over 4000) which makes me think one of your coils is shot.

Try 8 new plugs (make sure they're the right gap) and MAKE SURE YOU OIL THE THREADS!!!!!! someone didn't do that to Old George, and it ended up costing me a new head.
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Offline ffourc

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Re: revs limited and dies under full throttle...WHY????
« Reply #6 on: Nov 24, 2005, 08:51AM »
R31 *PINTARA* with a ca20 engine


easiest way to check coils/etc is to swap leads on coils see if then it revs over 4k

do a search this has been covered in u12 section

Offline fintelboss

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Re: revs limited and dies under full throttle...WHY????
« Reply #7 on: Nov 24, 2005, 02:56PM »
Problem fixed, the leads were on the wrong coils. runs great now. Thanks for your help womabt and ffourc.

Offline wombat

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Re: revs limited and dies under full throttle...WHY????
« Reply #8 on: Nov 24, 2005, 04:37PM »
 ;D been there done that. The firing order's written on the cap.

~laughs at you for doing something i've done before~

At least you didn't take it to a mechanic like i did!
« Last Edit: Nov 24, 2005, 04:39PM by wombat »
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Offline ffourc

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Re: revs limited and dies under full throttle...WHY????
« Reply #9 on: Nov 24, 2005, 11:12PM »
hey fantastic - someone who updates - let alone thanks

but now the bad news - fintelboss

prob is not really fixed -  as by swapping overleads you are now running your inlet side plugs from the coil that used to run your E side coils - hence not limited to 4k

your exhaust(E) side plugs are probably not firing now, either due to bad coil or bad power transistor, I know this happens as I had power transistors fail on the E side on both my u12 and a friends corsair. If you fix it (cheap - espescially if you self service wrecker) you should notice a slight power improvement.

Offline Jono

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Re: revs limited and dies under full throttle...WHY????
« Reply #10 on: Nov 25, 2005, 12:31AM »
On a side note, I'm pretty sure the exhaust side is on all the time, with the intake side cycling in and out.
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Offline ffourc

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Re: revs limited and dies under full throttle...WHY????
« Reply #11 on: Nov 26, 2005, 12:14AM »
sorry Jono but

the inlet side plugs fire to redline and the exhaust side have the 4k cut off

Offline wombat

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Re: revs limited and dies under full throttle...WHY????
« Reply #12 on: Nov 26, 2005, 12:36AM »
I'm with Jono. Inlet side fire all the time, exhaust up to 4000

It might be lower, because fintelboss's speeds all round out to 3800 revs:

35 in 1st, 60 in 2nd and 88 in 3rd are all 3800rpm.

I'll make a test light thing (light on = coil firing = much cheaper than twin tachos) to see which ones do what. Definitively solve the problem once and for all. Too many people think they know, and not enough people know for sure.
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Offline fintelboss

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Re: revs limited and dies under full throttle...WHY????
« Reply #13 on: Nov 26, 2005, 10:15AM »
So is the problem fixed or not? It runs great now, under full throttle and over 4k rpm, i assumed all was well. Or do i need to replace one or two of the coils? if its working i say dont touch it!

Offline ffourc

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Re: revs limited and dies under full throttle...WHY????
« Reply #14 on: Nov 28, 2005, 11:18AM »
Quote
I'm with Jono
?

Quote
if its working i say dont touch it!
define working? - the engine was designed to run with both I&E banks working.

get a timing light and put on E side leads, and see if they are firing. (or use old spark plug with large gap)

Quote
Or do i need to replace one or two of the coils
Quote
as I had power transistors fail on the E side on both my u12 and a friends corsair
more likely power transistor, but often is easier and not much more expensive to change the whole twin coil assembly - leaving you will a good coil/transitor for future if needed.

Quote
Too many people think they know, and not enough people know for sure
Yeah, but I have diagnosed and fixed this issue on 2 cars.

will the car run on just I bank - you bet
will it run better on both banks -
Quote
you should notice a slight power improvement
lower emissions (& therefore better economy - I'd imagine)

Offline cruizer

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Re: revs limited and dies under full throttle...WHY????
« Reply #15 on: Nov 28, 2005, 05:00PM »
The odd vibration may have something to do with your engine mounts cos i had that problem and are soon to put in a new mount and should fix the vibration...my 2 cents worth...someone correct me if i'm wrong

Offline Jono

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Re: revs limited and dies under full throttle...WHY????
« Reply #16 on: Nov 29, 2005, 10:06PM »
I'd say the vibrations would be the engine misfiring.
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Offline wombat

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Re: revs limited and dies under full throttle...WHY????
« Reply #17 on: Nov 29, 2005, 11:44PM »
ffourc, i'm not having a go... don't think that. I'm just one of those people who needs to know for myself, from a book, a mechanic I know and trust or with my own eyes.

I think this place is great, but sometimes people express their opinion and are wrong. You, sir, are not on that list.
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Offline ffourc

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Re: revs limited and dies under full throttle...WHY????
« Reply #18 on: Nov 30, 2005, 09:51AM »
I didn't think anyone was having a go. All I was doing was saying this time I knew what I was talking about, so fintelboss could use my info and fix this I&E firing issue, if he chooses to.

 I know I can make mistakes/be wrong just like anyone else can.(but not this time)

Wombat, the ? was about you saying you agreed with Jono about I side cutoff, but wrote E side cuts out at 4k (which is what I said - but I was not as clear as I should of been( it by mentioning I/redline))like now?

Offline wombat

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Re: revs limited and dies under full throttle...WHY????
« Reply #19 on: Nov 30, 2005, 10:26AM »
i put myself in the people who think they know category.

I know one side cuts out. I don't know which side. That's why I'm making the test rig to work it out. Geregory's manual doesn't say which side does what, I think the series 3 bluebird one does...
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Offline ffourc

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Re: revs limited and dies under full throttle...WHY????
« Reply #20 on: Dec 1, 2005, 11:33AM »
FSM(u12) says switches from 2-plug ingnition to 1-plug during heavy engine load driving to reduce engine noise.

afm(amount of air) & distributer(hall sensor-engine speed) ---->ECM --->power transistor(Exhaust Coil)

ie. exhaust coil is the one that is switched

Quote
It might be lower, because fintelboss's speeds all round out to 3800 revs

you're likely right as 3800rpm (or below that if high engine load) is when the "mixture ratio feedback system" stops operating.

mixture ratio feedback system = closed loop = exhaust gas sensor values are used to alter injector pulse to maintain stoichiometic point (14.7:1 air/fuel)


Offline Jono

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Re: revs limited and dies under full throttle...WHY????
« Reply #21 on: Dec 2, 2005, 10:57PM »
If you have a look at the connector for the coil pack, 6 of the wires are paired with a lonely looking 7th wire (grey from memory). The coil that wire is connected to is constantly on, because that wire can be used to drive a tacho.
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Offline FeralMonkey57

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Re: revs limited and dies under full throttle...WHY????
« Reply #22 on: Aug 20, 2013, 05:11PM »
I'm having similar problems since I bought '86 GXE Pintara from my old man with cut off at 4000 rpm.... I replaced new rotor that hit redline without problem.