Acceleration problems - Toyota Nation Forum : Toyota Car and Truck Forums

awildman · 08-31-2009, 08:42 PM

Hi, all. I own a base model '94 Corolla with the 1.6l 4afe engine. I've been tackling a bunch of little repairs/maintenance lately. It's been worry-free for 210,000 miles, and I'm extremely happy with it. I've had this car for over 150,000 miles now, and haven't been the most regular with oil changes and such, but even so it's been fabulous.

The biggest problem (other than the timing belt being 200,000 miles old) is that the car is not as powerful as it used to be. I just replaced cap and rotor and that helped a bunch, but didn't cure it. The problem is most noticeable in first and second gear. More power at higher RPM's, and not just the powerband of the motor. Right when I'm ready to shift out of first gear, I get a significant surge of power. Same scenario in second gear; right about 30 mph it gets a nice surge of power.

I'm thinking that this is a compression problem: worn out rings, tapered cylinder or the like. It could also be a fuel-related problem. I get a decent whiff of raw gas first thing in the morning, but the acceleration problem happened long before the raw gas smell. Recently changed the fuel filter, so that's not it. Is this a typical problem? What else could it be? TPS sensor? Thoughts?

Question B: I'm replacing the timing belt tomorrow, and I'm concerned that the belt might be one notch off. Not likely, but possible. If that's so, how do I make sure to set it correctly? And can the ignition timing be adjusted at all? Used to be able to adjust ignition timing on old cars via the distributor, but my Haynes manual isn't clear on this at all. Any suggestions greatly appreciated.

Question C: How do I set the timing belt tension correctly? The book says to use a belt deflection gauge, but at $300, that's out of the question. Is there a cheaper option, or do I just do the educated guess thing?

Cheers,

Aaron

Bitter · 08-31-2009, 09:00 PM

it sure does sound like the timing is off a tooth, does it idle a little roughly too? the timing belt can stretch and throw the timing off.

iToaster · 08-31-2009, 09:02 PM

The A series engines tend to make power in the high revs, but as your engine gets more miles you'll naturally lose power with carbon buildup, engine wear, and whatnot. You might want to look into running some Seafoam through it to clean it up a little. If the timing belt was a notch off the engine would, if anything, most likely barely idle and would probably die when given gas, so I doubt it. It's like most other engines, you've got your degrees for lining up TDC and a notch on the crank and some notches/holes on the cam gear. The belt should be fine if you can turn it to about a 90 degree angle by hand, no more.

awildman · 08-31-2009, 09:31 PM

It idles just fine. Probably not off a tooth, since the only symptom is loss of power at low rpms.

@iToaster: there are marks on both the cam and crank for that sort of thing, but even so it's not hard to be off one or two notches. I did the timing belt in my ex-fiancee's Hyundai a few years back and even though I paid attention it was off a notch the first try. I did run some seafoam through my car awhile back and nothing came out. Either the carbon's in there good or not at all. Probably just engine wear. I'll do the timing belt and lifter shim adjustment procedure and find out if that helps at all. Two years of delivering pizzas in it weren't kind.

Corpsey · 09-01-2009, 03:58 PM

I was having similar problems a while back. Do you have an engine check light that will flash a code at you on hills??? Mine has 365 000 I did the timing belt, cap, rotor, plugs, wires, and I'd definitly replace the fuel filter cause mine had a huge clog in it. Now she runs WAY better. Hope this helps

gameguru1360 · 09-01-2009, 05:44 PM

an alternative to seafoam is the Marvel's Mystery Oil which is a slower and gentler cleaner for the car...you can add it to the crankcase, auto tranny, gas tank and power steering reservoir. For right now, I'm only putting it in the gas tank...4oz for every 10 gallons at fill up. I think the seafoam is more for cars that still have carburetors

kevmac · 09-01-2009, 09:12 PM

as mentioned, did you change the plugs and the plug wires?

seafoam, fuel filter, change your friggin oil!

, and your coolant

and your trans fluid + diff

, and brake fluid

and power steering fluid

and air filter

If you burn, you may need a thicker oil to help, but as my coworker (a mechanic) pointed out, the cam will suffer

awildman · 09-01-2009, 10:42 PM

@ corpsey: No check engine lights. Ever. I just changed my fuel filter for the first time at 210,000. I always use Chevron gas and there was nothing wrong with the old filter at all. Not even a hint of debris.

@kevmac: in the last month i've done the following: oil, coolant, man trans fluid(no diff on manual Corollas), power steering fluid, air filter, fuel filter, cap, rotor, plugs, thermostat. Still need: plug wires and brake fluid flush.

When I took out the plugs for the timing belt procedure today, I looked down into the cylinder. The pistons are *extremely* built up with carbon. Only on the #2 piston could I see any metal at all. I think that's the root of my power loss at low RPM's. Now to figure out how to remove that....

awildman · 09-01-2009, 10:55 PM

The thermostat has been weak for awhile. I think it was stuck open, causing the engine to run cold. I hear this can cause excessive carbon buildup. Will running the engine hot(high rpms, big hills, etc) clean it out?

kevmac · 09-02-2009, 05:56 PM

You want the temp gauge to look broken and point right in the middle at nine o'clock all the time no matter whether cold and hot weather. If it is higher then it is running hot, if lower then it is running cold.

Make sure you replaced the thermostat with the factory spec match and not a lower temp part. Drive around a while until the stuff heats up. If those wires have 200k+ then they are long over due and probably high resistance by now. That could definitely reduce the spark intensity= less efficient= more carbon waste. Consider seafoam, there are chapters on it here.

penguin0123 · 09-02-2009, 07:29 PM

Or use BG44k. I used a can of that stuff, and it improved the MPG from 28 to 32. The power feels as squishy as ever, but at least I'm not burning as much gas.

kevmac · 09-02-2009, 08:48 PM

Whatever you do, be careful not to overdo it. All that shit has to go somewhere. It will cover your plugs and might throw cel's after treatments (not to mention the cat reaction).

I would look for GM Top Engine Cleaner if I had that black crap you described, but I'm not sure you can still buy the seafoam form of it. It is hardcore and makes seafoam puff like candy cigarettes.

trife96 · 09-02-2009, 09:05 PM

Seafoam, change timing belt. You have to be hearing some valve clatter with that many miles on the original belt. That will make a good bit of difference. Also wouldn't hurt to do all the other things like air filter, oil, oil filter. Fuel filter, plugs wires, rotor and cap

awildman · 09-02-2009, 10:38 PM

New thermostat is factory spec, 180 degrees. Valve clatter? Nope.

Timing belt came out. Looks like an aftermaket Gates belt. Had to have been changed before I got the car. Didn't look too bad. Little bit of wear on one side of the belt, couple of minor cracks. Definitely time to change it. What realy PO'd me is that whoever did the work lost 4 of the bolts holding the 3 timing covers on. Not only that, but they gouged the heck out of the top two covers, even breaking the top one a bit. Shoddy work.

And to top that off, I'm replacing the water pump while I've got it all apart, and the dealership gave me the wrong one. I'm not happy about that. I'd be driving my car right now if it wasn't for them.