Do I Have Carby Problem...?

[ac17]

Hi all I found this forum via a Google search and thought I might post here.

 

I am now the proud owner of a well-cared for 1987 AE82 4AC manual corolla liftback (seca), with only 118,000Kms on the clock.

 

I am having probs I did not pick up during the test drive - when coasting in 3rd or 4th (eg anywhere between 2000 and 3000 RPMs), I notice that the car is having mini flat spots (or stutters), but when I floor it and rev higher than 3000 RPMs, the car has heaps of grunt and the problem goes away.

 

What could be wrong - is it a carbie issue?

 

MORE INFORMATION:

-the car idles smoothly

-the problem does not happen much below 2000RPM

-the slower you work up speed, the more pronounced the problem (especially if you sit at a speed / RPM between 2-3K RPM: eg 50-60kms in 3rd)

-the car is often difficult to start and seems to need a few pumps of the accelerator

-Problem occurs when hot and cold

 

 

 

I HAVE DONE:

-I have changed the leads (no difference)

-I have inspected the spark plugs (they look pretty new. Light black dust coating. PLUS THE CAR IDLES WELL AND HAS HEAPS OF POWER)

-I have measured the Ignition coil with multimeter (it's the same prim and 2ndary voltage as a new one at repco...)

-I have tried premium unleaded and no difference

-I have added acetone to fuel (90 mls per full tank gas) and no difference

-Car has near new battery

-Distributor and rotor look in fairly good condition (plus she idles smooth and has heaps of power)

-I have sprayed inside Carby with carby/injector cleaner (no difference)

-Air filter is near new

-I Replaced the fuel filter last week

 

 

 

I have looked on forums everywhere and can't get to the bottom of this...

 

ANY IDEAS???

Edited December 24, 2010 by ac17

[altezzaclub]

Looks like cleaning the jets in the carb is next on the list. The accelerator pump seems to be working, and the scond choke as it all goes when you floor it, but either getting onto the main circuit or that main jet itself might be partly blocked so its running lean. One possiblity anyway-

[clubby2084]

Get the carb rebuilt and have them look at the jet sizes. This was the cause of the surging with my carb (the stuttering at 2000 - 3000rpm you mention).

I ended up paying for a Dyno Tune. This allowed the mechanic to see exactly where the carb was (and wasn't) performing through out the rev range and under differnt loads. Wasn't cheap, cost close to $800 for bits and pieces and the tune (this did not include the cost of a carby rebuild as that had already been done previously).

Holy Crap - what a difference. Expensive, but the difference is amazing. Drives like a new car.

[Sloth]

A dyno tune would be my recommendation as well. I had a similar sort of problem with my 7k (runnign twin SUs), when I put my foot to the floor it was fine, but after that it would cough, splutter and stall for about 10 minutes. Chucked it on the dyno and the discovered that I had the wrong needles. As clubby said, it isn't cheap (I had a similar sized bill) but it was definately worth it (drove in doing like 42rwkw drove out with almost 60.

[ae824ate]

I would also be inspecting the jets, and taking the top of the carby off to check the bowl for crap at the bottom. Probably worth checking your vacuum hoses are all good too. There are a few threads on here concerning 4a-c carbies, might be worth a search. Good luck.

[Trev]

Is it running at temperature?

 

They can flat spot if running cold.

[ke70dave]

did you spray the inside of the carby with the engine on?

 

and rev the guts out of it while your spraying it in?

 

might pay to get a carby kit for it, they can be had for pretty cheap.

[BReNt]

This is pretty dodgy but it's worth a try lol.... and if it works it's usually only a short term solution to the problem but anyways...

Cross two leads over, start it up and let the car backfire. This can sometimes clear out a heap of shit that's stuck in the carby.

 

EDIT: Take out your air cleaner/airbox before doing this.

Edited December 26, 2010 by BReNt

[Trev]

Cross two leads over, start it up and let the car backfire.

 

Lead 2 & 3.

[ac17]

Trev - it happens no matter the temperature.

 

Re carbie cleaner - I took the air filter off and just sprayed inside while engine was running (which stalled the car). I did not rev the guts out of it. It was a little harder to start afterwards (but no harder after it ran for a few mins)

 

Someone at Repco said about my description of the problem "it sounds like it's the secondary diaphragm... take it to burwood carby.

 

My mate's dad just reckons I should live with it, as the car cost $1500... But it does still BUG me...

 

Now for a stupid question: is it possible to retro-fit EFI from a wreckers so I have EFI instead of a Carby and all its problems?

[Trev]

4ace efi is a bit hard to find, best to source it from NZ, anything else is just a waste of time IMO (Ford TBI etc) and you would be best off with a full engine conversion.

[ac17]

Hi all !

 

I think I am narrowing it down: E10 PETROL!!!

 

After my car running really well for a few weeks on premium unleaded with 90 mls pure acetone per tank and then still running well on some 95 octane fuel I got at a Mobil (eg 430kms off 37 litres, mixture of city and hwy driving with car fully laden for at least 140kms!), I just filled up an almost empty tank with E10 and to my dismay, the car would barely start!

 

Have had the problem return on me and have no power!

 

I was able to change from 2nd to 5th and car had pick up, and now it feels like i have the hand brake on!

 

I just did some googling ("E10 car problems") and found a few things:

1. E10 is not suitable for all cars - even many cars made in the last 5 years

 

2. E10 is generally not suitable for cars pre 1986, or with carbies

 

3. E10 has a high water content and corrodes steel tanks (like those present in cars pre 1986) and can corrode other engine parts

 

4. E10 corrodes gas station tanks and pumping equipment, unless specially designed to take this watery gunk!

 

I read tons of forum posts of motorcyclist and car owners who all complained about it, and then an NRMA article saying "E10 will be replacing unleaded petrol from July 2011".

 

CHOICE magazine also has done an online article about it...

 

So - E10 is SHIT.

 

Mind you car was still not totally perfect: Starting was harder when warm, and it has some flat spots occasionally in 1st or 2nd when flooring it, but the problems of stuttering I originally posted about had vanished! - I suspect there was still some E10 in my tank and it was gradually being flushed out by the better petrol, or as suggested, maybe I do have some carbie probs which are minor when compared to the carnage caused by just one full tank of E10.

 

Anyone else used E10in their rolla? (mine is carbie - a 4AC)

[beerhead]

E10 needs the timing advance taken up a bit too. If the jets are a bit clogged it won't be very happy about it.

 

A really quick easy was to clean your jets is to take the air filter off and put 1 hand on the throttle. Rev the motor up to about 4 grand and then seal the top of the carby with your other hand, taking your hand on and off quickly while feeding the throttle to keep the car running. Now if the motor won't start after this it's because the car is now overfueling, you'll have to screw the idle needle in until it starts, and then get the idle screw right.

 

The extreme vacuum in the motor sucks all the crap out of the jets. I've seen motors that would not start or even idle run like a dream after doing this trick :)

[ToasticlesAe82]

Yeah i hear all of you, my 4a-e carby has given me quite a few problems, taking a can of carby cleaner to it every few weeks or so seems to do the trick for me.

 

Now drive another daily driver so i will have time to work on a 20valve engine swap where carby will not give me any problems :) fuel injection wins.