1. Home
  2. Automotive Technologies
  3. 91 Toyota Camry: Emissions/Ignition question

91 Toyota Camry: Emissions/Ignition question

I have a 91 Toyota Camry Le with 181 K miles on it. It recently failed the Texas emissions test on the hydrocarbons part of the test. With a standard of 123 ppm hc at idle, my car scored a 200 ppm. At higher rpm's, my car missed by just a little. As hc problems are often associated with poor ignition, I am in the process of checking out my ignition system (e.g., plugs, wires, etc). Today, I was checking each cylinder by grounding out each plug wire to see how much the the rpm's changed. With one of the wires, when I pulled the plug wire, I noticed a snapping (electrical) sound coming from the area of the distributor. I assume I am getting voltage leak from that area. What would cause this? Also, why would it show up when I pulled the plug wire and grounded it?

Second question: I notice when I placed a tach on the engine that my idle has a little "bounce" to it. In other words, it is fluccuating between 640 and 660 rpm's at idle. What would cause this? Would it indicate arcing or something similar occuring in my distributor? I would appreciate your opinions on this.

Thanks, Al Kondo

Reply to
Al Kondo
Loading thread data ...

You've got a good idea checking the secondary side of your ignition system, but you're much more likely to cause damage than to make much headway using these 1960s diagnostic techniques on your '90s car. Pulling and grounding spark plug wires is a terrific way to burn out some of the electronic components of your engine management system, and it's also a good way to heat up and kill a catalytic converter, if you dawdle.

By all means, make sure the wearable ignition components are in good condition, but you may need an O2 sensor or any of many other components that must be examined with the proper equipment.

DS

Reply to
Daniel J. Stern

Your problem could be caused by not getting good sparks in a timely fashion (fouled spark plugs, bad spark plug wires, bad distributor, bad timing). However, it seems to me the most likely explanation for your high HC (if CO is low), would be a really small vacuum leak or a worn out exhaust cam lobe. You can verify this by attaching a vacuum gauge to a vaccum port on the manifold. If you see the needle fluctuate instead of being stable you have a vacuum leak. This explanation would also account for the variation of idle speed you are experiecing (however small). If you are also getting high CO readings, it could be caused by getting too much fuel into the cylinders (leaking fuel injector, failing fuel pressure regulator) or a failing sensor that is sending wrong data (oxygen sensor, map sensor, TPS). Keep us posted on your on-going saga.

- JR

Reply to
JR Lomas

I mentioned my low idle rpm (600 rpm's), and I wonder if it could be a partial cause of my emissions problems.. My manual says my 91 Camry LE should be reading about 800 rpm's at idle. What would cause this?

Thanks, Al Kondo

Reply to
Al Kondo

try

formatting link

it's a good group

Reply to
Killinchy

MotorsForum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.