Corolla down on power. Ideas?

MikeWhitney · **Joined:** Wed Aug 20, 2003 9:15 pm **Posts:** 4724

Or do they all do this?

I now have a 1989 Toyota Corolla for rallycross use. It's nothing special. In fact it's kind of a POS.

16 valve carburated 1.6l engine - 4AFE (thanks Scott for the correction)

Motor starts, idles, and revs fine (revs to redline). Good mid-range torque, but the power seriously falls off over 4k RPM. The car won't even redline. In 2nd gear it gets to 5500 rpm and just makes a lot of noise.

Any ideas? Anyone know these engines or cal loan me a shop manual?

Ideas so far:

Plugged cat
Fuel filter
?

Scott Johnson · **Posted:** Fri Jan 30, 2004 12:13 pm

It's a 4AFE not GE.

Since it is the 4A, check at www.club4ag.com, there are enough people out there with non-4AG corolla's that you might get some good tips.

Otherwise, as mentioned, plugs, wires, cap, rotor, carb cleaner.

Even better, shop around for a used Formula atlantic motor and bolt it in there... 10,000+ rpm, etc.

Scott

Kevin Allen · **Joined:** Thu Aug 28, 2003 6:42 pm **Posts:** 3479

I had a similar problem with an 86 Prelude - it ran fine up to whatever rpm it was, then power made a sharp decrease (but it still accelerated). Something had come loose inside the distributor and was rattling around above that rpm. The mechanic identified the problem when he saw the cracks that were forming in the distributor. I think it was replaced with a junkyard distrubutor for around $200.

Good luck!

DickRasmussen · **Posted:** Fri Jan 30, 2004 4:10 pm

Additional ideas (basics which you probably have checked):

Air Filter or related plumbing seriously plugged (we found a large stash of bird seed in the intake to our old Nissan one time).

Carb choke not opening.

Does the carb have a progressive secondary which isn't opening?

Since you mention rpm, I assume it has a tach. Is the tach "smooth" or is it bouncing, etc. If not, my guess is that it is not an electrical missfire. However, it could be a distributor which is not advancing the timing to max based on rpm.

Plugged cat or other area of exhaust sounds like a good candidate . . . especially given its rallycross use.

Keep us posted.

Joseph Volk · **Posted:** Fri Jan 30, 2004 4:29 pm

If it is a clogged cat, the usual tell tale sign is when you let up on the gas, you will actually have more power.

Fuel pump or fuel filter from your description of the problem is my guess.

Scott Johnson · **Posted:** Fri Jan 30, 2004 4:52 pm

Hmm, Dick has some good ideas there. Set #1 to TDC (or BDC, who cares) and pull the distributer cap. Take note of where the rotor is points (important).

Pull the distributer and clean it a bit. Make sure the advance weights move freely (you should hear them clacking a bit if you spin the distributer shaft). WD-40 in there shouldn't hurt anything.

Put it back together with the rotor pointed to the same place. The carb choke and secondary are good things to consider too (assuming it's a 2bbl carb). The secondary is probably on a vacuum line somewhere, so if that is clogged/broken, then you are stuck with a 1 barrel carb.

A new fuel filter is probably in order too.

Scott

Rob Keehner · **Posted:** Fri Jan 30, 2004 9:48 pm

I think it just need NAWZ.

DickRasmussen · **Posted:** Sat Jan 31, 2004 10:46 am

scottjohnson wrote:

The carb choke and secondary are good things to consider too (assuming it's a 2bbl carb). The secondary is probably on a vacuum line somewhere, so if that is clogged/broken, then you are stuck with a 1 barrel carb.
Scott

IF the carb "secondary not opening" idea is an actual possibility, it could be something simple like the vacuum line. Or it could be something subtle. My first Mustang (1969 351 4V) had a Ford carb. To make a long story short, the carb had a "suction piston" that pulled the secondaries open. It would gum up (even with an almost new car) and the secondaries wouldn't open. Symptoms were similar to yours (hence the suggestion). Solution was to manually unstick it and/or spray carb cleaner on it. More effective solution was to floor the throttle more often so the piston didn't have a chance to gum up.

Wes Eargle · **Joined:** Mon Oct 27, 2003 9:47 am **Posts:** 3683

I'd say Berryman's B12 the bejeezus out of it. Between that stuff, WD-40 and duct tape, you can solve any problem.

Marty Howard · **Posted:** Mon Feb 02, 2004 4:57 pm

I would check the Fuel Filter and carbs first.

I had a 2T-G that started Fuel starvation at about 4800 RPMS, new filter did wonders, that and carb cleaner.

MikeWhitney · **Joined:** Wed Aug 20, 2003 9:15 pm **Posts:** 4724

DickRasmussen wrote:

IF the carb "secondary not opening" idea is an actual possibility, it could be something simple like the vacuum line. Or it could be something subtle. My first Mustang (1969 351 4V) had a Ford carb. To make a long story short, the carb had a "suction piston" that pulled the secondaries open. It would gum up (even with an almost new car) and the secondaries wouldn't open. Symptoms were similar to yours (hence the suggestion). Solution was to manually unstick it and/or spray carb cleaner on it. More effective solution was to floor the throttle more often so the piston didn't have a chance to gum up.

Dick - sounds like this carb works exactly like the ford carb. It's 2 barrel, and the secondary opens with "help" from a suction piston. We took it apart and nothing seems obviously wrong. How can it be checked for proper operation? Presumably it will only open when the engine is under load?

Revving in neutral makes the secondary open slightly, so at least it's moving. All the pieces appear to be clean and ungunked, but who knows?

MikeWhitney · **Joined:** Wed Aug 20, 2003 9:15 pm **Posts:** 4724

New fuel filter - check
Clogged cat - nope, and it will never be clogged again

Choke opening fully - yup
Throttle linkage adjusted - ok

Any other ideas? We should get this car on a dyno - then the secondary could be checked under load!

MikeWhitney · **Joined:** Wed Aug 20, 2003 9:15 pm **Posts:** 4724

scottjohnson wrote:

It's a 4AFE not GE.

Since it is the 4A, check at www.club4ag.com, there are enough people out there with non-4AG corolla's that you might get some good tips.

Scott

Scott - I started a post over there and I have discovered that it's a 4A-F not a 4A-FE. Apparently the "E" means EFI. And apparently there is such a beast as a 4A-FE. Let me know if you ever see a EFI setup from a 4A-FE for cheap

Scott Johnson · **Posted:** Tue Feb 03, 2004 4:15 pm

MikeWhitney wrote:

scottjohnson wrote:

It's a 4AFE not GE.

Since it is the 4A, check at www.club4ag.com, there are enough people out there with non-4AG corolla's that you might get some good tips.

Scott

Scott - I started a post over there and I have discovered that it's a 4A-F not a 4A-FE. Apparently the "E" means EFI. And apparently there is such a beast as a 4A-FE. Let me know if you ever see a EFI setup from a 4A-FE for cheap

Sadly I knew that but didn't really think about it. I just get so used to EFI being on everything. Since the hood is off of the car, just clip a mirror somewhere that allows you to see into the carb from the drivers seat and go for a drive.

Scott

Scott Johnson · **Posted:** Tue Feb 03, 2004 4:19 pm

Problem solved... though it more than doubles the cost of the car.

http://cgi.ebay.com/ebaymotors/ws/eBayI ... 2456697274

1.6 liters, 100 hp/liter, 20 valves, 4 throttle bodies...

Scott

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Corolla down on power. Ideas?

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