Armed with the invaluable EFI manual, thoroughly and painfully scanned and emailed by Ian Dunse (many thanks), and the tips by David M and Dave B, I went to a couple of friendly garages to exchange views regarding my problem “described in an earlier post Smell of Unburned Petrol”. They both told me that the middle “exhaust box” is actually a Catalytic Converter (?), and most likely the source of the bad smell and fuel drinking. And to finish a dead horse, i.e. me, they both shot
If your car was originally equipped with a catalytic converter, which looks like, then the engine was designed to run on unleaded fuel (petrol), only. Using leaded fuel, as you have been (for the 15,000 Km), has definitely ruined the catalytic converter.
How true is this (for my 1989 EFI)?
The only options I see are
1. Start using ULP
Not an option in southern Afr, only a couple of high end pumps in town can supply ULP and my Townace isn’t exactly intended for the town. Or should it?
2. Keep using LP
Yes, but what are the drawbacks other than the Catalytic Converter? And fuel consumption?
3. Remove the Catalytic Converter
Yes, I am really tempted, but what will happen? Will the engine performance degrade? Will I have a dashboard indicator permanently ON?
4. Keep the Catalytic Converter?
To what use exactly, isn’t it the cause of the bad smell due to being clogged?
5. Sell the petrol townie, as a slave, and buy a diesel townie?
Humm, but only as a last resource. BTW, what would you tell your wife and kids, before selling the home dog?
Sorry for the long post. Any HELP on the above will be much appreciated.
Thanks
Manecas
- (#8089) Manecas, 14 Apr 03 11:43
Hi Manecas
If you have been running an unleaded engine on leaded petrol, then your cat will have been destroyed, and will need replacing, or removing.
The catalytic converter is designed to remove some of the harmful emissions from the exhaust, and you don’t actually need it in order to run on unleaded petrol.
If you decide to stick with leaded petrol though, you had best remove the cat altogether and retune the engine. This is important as the timing is either advanced or retarded to run on unleaded. I cant remember which, but if its retarded, then your engine will run hotter, and you may experience some over heating problems.
“Will the engine performance degrade?”
When the UK government decided to outlaw leaded petrol many years ago, one of the main arguments put forward by people who wanted to keep it, was that unleaded petrol would greatly reduce the performance of all cars! All these years later and we still have high performance cars running very well on unleaded petrol.
Glad you got to the bottom of it, sad its not an easy fix
all the best
dave Bright
- (#8090) dave Bright, 15 Apr 03 1:02
Manecas, not totally convinced the catalyst is the cause of your smell. As you're in a country not known for emissions laws, I'd either remove the cat completely or (if you can) put a bar down the exhaust and beat it, to break up the innards of the cat, removing it's obstruction. The garage can test whether the cat is blocked by putting a pressure gauge on the pipe before it.
Removing the cat would only cause a warning light if the vehicle has two oxygen sensors, one before and one after the cat. As far as I know only Californian models have this feature, so you should be OK.
Remove the cat by whatever means and report back...
(oh, and just use leaded petrol- I'm sure most people in your area do...)
- (#8091) david miller, 16 Apr 03 1:47
David, Dave et al,
Many thanks for the most valuable clarification and advice. Profiting from the long w'nd, went to a SAf exhaust specialist (Supa Quick) for a removal and replacement of the entire thing. They fitted stainless steel pipe and two boxes, and after calling local Toyota, bolted the probe (sensor?) extracted from the catalytic convertor, into the chassis body(for grounding?). However, with or without it, no warning light. All, parts and labour at 1600 SAf Rands (+/-135 GB Pounds)
Then visited an EFI techie, who (quite impressed) performed the tests suggested here, on the diagnostics socket, matching the error codes (I had a full printout including that of the scanned manual, by Ian D). He cleaned the air flow meter, then did the measure of CO emissions (from a machine connected to the townie battery, with a probe into the exhaust pipe, which returned figures ranging from 0 to 0.6, on idle and revving to about 3000rpm) His conclusion was “running too lean, which is actually good”. He could find nowhere to adjust air/fuel, which led him to believe this model has preset values (!?). The only thing he could adjust was the idle, up to 750rpm, which had dropped to about 500rpm (after cat removal). Is this finding reasonably acceptable?
Conclusion
1) The crude smell appears to be gone for good (had a 300km drive back at mixed speeds 90k/h -140k/h and both myself and a cousin, could not feel it anymore), 2) There is a much improved responsiveness, slight kick on pedal and vuuuuuuuuuummm, 105 k/h and finger bells! 3) Fuel consumption did not improve dramatically, averaged 12L per 100 Km). For this one, and to take on the techie’s offer, I will be going back, to bury the viscous fan and have an electric fan installed.
I will be watching carefully the performance(and measuring the fuel consumption), before and after the electric fan and will report back, whether my own findings confirm the so much desired MPG improvement.
Again, many thanks, your tips made a good difference and you bet, option 5 (above) is out of now question (same for 1 and 4).
Manecas
- (#8194) Manecas, 22 Apr 03 10:35