1995 Toyota Corolla - Driving me crazy

Maintenance/Repairs
41

It has been awhile but the timing is set by the ECM. The distributor has a camshaft position sensor inside it to tell the ECM where the engine is and the ECM fires the plugs based on that information along with a lot of other information.

IIRC, there is a plug you disconnect from the distributor or maybe one you put a shunt into, whichever, that sets the timing to a fixed point based on the cam position sensor. You make a small adjustment to the distributor to adjust that to the timing marks on the engine. Once everything is returned to normal, the timing is controlled by the ECM.

As for idle speed, there is no adjustment. There maybe an IPS (idle position switch) or the ECM maybe uses the TPS (throttle position sensor) to determine when you have taken your foot off the gas. When it determines that, the ECM takes control of the idle speed. If you go messing with any screws on the throttle body, then the system won’t work right.

No way any mechanic can say the belt is correctly timed by listening to it. He’s blowing smoke up your keister. This is a non interference engine so a slipped timing belt will not cause parts to hit inside the engine so there won’t be any unusual noise.

42

Once I bought a car (1996 Subaru Legacy) having 120K on odometer and that thing definitely had some engine problem, as idle was stable, but the higher it went on RPMs the more of instability it showed.
I wanted it to be a project car, wanted to learn how to troubleshoot/fix opposite engine.
As I prepared everything for the engine disassembly in my garage, I found that whoever was replacing the timing belt on 2.2 liter non-interference engine it had, misaligned it by 1 tooth.
My project ended way too soon :slight_smile:
Performance improved a lot, car was driving literally anew after the correction.
I’m not sure how long after botched belt replacement prior owner drove it, but apparently they sold the car because they could not make it work as it worked before, I bought it dirt-cheap.
@Geo48, does it ring the bell anyhow?

3 Likes
43

You’re wrong

The distributor does NOT have slotted holes

You literally can’t “make a small adjustment to the distributor to adjust that to the timing marks on the engine.”

I know this for a fact, because I owned a 1995 Corolla with the 7A-FE for many years

As I said before, there were some earlier 7A-FE engines which did have slotted distributor mounting holes . . . but not on a 1995 Corolla

44

OK then I stand corrected.

1 Like
45

You’re so right db4690. No adjustment. No slotted holes. All done by ECM.

Thx, man. And tkx, Keith, too.

geoccohen@aol.com

46

Could be, greendragON. I’ll check the cam timing. Thx.

47

I wonder how many degrees rotation a single cam tooth interval represents? It’s sort of hard to believe being off a single tooth would cause the engine to misbehave much, other than the power might be noticeably reduced. Longer 0-60 times. And emissions increased. But I’ve never done the experiment either.

48

Have you read the OP’s original complaint ?

49

Did OP say the problem was the car wouldn’t go over 25 mph? That’s not a symptom I’d expect by being one tooth off? A difference in 0-60 times of 10 seconds vs 15 seconds maybe.

50

Once the belt on my 1975 Civic jumped ahead one tooth.
Ran normal until it got over ~3000rpm (no tach) and heavy throttle.
Revved up fine in neutral.
Went down a rabbit hole thinking it was an issue with the carburetor’s secondary venturi.
Finally got around to checking ignition timing and it was advanced ~15 degrees IIRC.

1 Like
51

Thx, guys, so much, for analyzing my situation with the “Beauty,” (I call her). 1995 Corolla. What does OP mean? Original . . something?

52

Thx, circuitsmith. I will have to check ign. timing and cam timing. I’ve been putting off doing that. Main reason? The guy who put in the new t-belt 1 1/2 year ago said, when I brought it back a few months ago, that it was not the t-belt. He was a Hollywood Toyota mech. and said that his first car was the '95 Corolla. So I took his word as his hearing the engine and jiggling the butterfly. Even at a standstill, the car still cuts out, chokes, and stutters when any throttle is applied.

53

Have you cleaned or replaced the throttle body

54

O P----Original poster the one who started the post

55

No, Barr01, I haven’t cleaned the throttle body. Good advice. Thx.

56

Roger that, renegade. OP, that’s me.

I guess that I take the T.B. off and clean with carb cleaner spray, yes?

3 Likes
57

With that age car—always start with the simple first------------sounds like a vacuum problem—check all plastic vacuum lines under the hood—might have a cracked or broken one somewhere-----The vacuum lines are all tied into the system----

58

Not likely to be a vacuum issue unless it is a component that is fed by vacuum. A vacuum leak at the intake manifold usually causes poor idle but as the throttle opens up, the fuel/air ratio is less affected by the vacuum leak.

So little air is leaked by most vacuum leaks, even a broken vacuum hose that their greatest effect is when the throttle is closed. As the throttle is opened, the amount of air provided by the leak is far less than what is coming through the throttle body. But id the broken vacuum hose feeds something that otherwise controls timing or fuel feed, then that is a different story.

59

Thx, Samuel. Say, if I had a vacuum guage, can’t I just check the vacuum to see if it’s normal? Would that then t/s the whole vacuum system? Just askin’

60

I see, Keith, The idle is perfect, smooth, can’t even feel the engine. Any application of throttle (pedal or under hood by butterfly) produces the "uh, uh . . . uh . . uh . . . uh. I’m worried that after a year my CV joints are getting worn out (replaced a few times in the past 14 yrs). If the gas is applied VERY slowly, it will get smoothly up to 25 mph or so, and no more.

Oh, a very interesting thing (I tell you b/c I think you know a lot). The speedometer is understating the mph. At first on a drive the mph stays at 5 mph. I know for a fact I’m going 25-30 mph. It takes about 10 mile when the speedometer comes up a bit but not the regular speed. I thought (months ago) that, "I’ve got it! It must be the instrument cluster! Before that I changed the VSS two times. No change. Eng. still choking along. Then I changed the instrument cluster two times, as below. (both U-pick). No change.

Before this I changed the TPS. I also checked out the ohms there. It was good. It’s easy to change.

In all my t/s over the past year, I changed the instrument cluster two times (U-pick). Reading the official Toyo Corolla manual that I have for ten years (4" thick!), in the VSSensor section it says, “Hint: If the speedometer is working normally, the VSS is good.” I changed the VSS anyway. One time from a U-pick VSS and then a brand new one.

So, finally, after starting out in morning, the speedometer is understating the MPH for about ten miles (it still only gets about 1/2 to normal speed). So, I’m thinking, what is the cause of this delay? The engine heats up. But heats up what?

So, I’m thinking that it may the ECM. Or maybe it’s oxy sensors (2) or EGR. The big prob. is, I don’t have the money to have it checked out. So I do it myself. Over one year now! I keep chugging along (with ppl honking and giving the finger, etc. I give it back).

Oh, one final strong point. The official manual says that with certain input signals to the ECM, it goes into “fail-safe” mode, or aka, "limp"mode. That’s just so that you can get home. There is a separate microprocessor in the ECM that does not advance timing and maybe not adjust fuel/air mixture. I think it’s the ECM.

What say ye?