Quick question before I do any damage. I have a 1981 308 with an aftermarket Motec M48 fuel injection system on it. The problem is two fold. I live at over 7,000 feet altitude and the car runs rich (or I believe its running rich) . I also have test pipes on the car with NO cats. I am not exaggerating in the least to claim this car is absolutely impossible to drive, it handles fine but literally kills every insect within 5 miles the fumes are so strong. If I start the car in the garage, the house smells of fumes. Once I was dropping my wife off at a dealer and just sitting in the parking lot for five minutes caused the dealer to think there was a gas leak and evacuate employees until I explained it was my idling car .. LOL. Its so bad that at hwy speeds my wife following me can smell the exhaust. Or at stop lights its truly unbearable for all cars around me. With that said, I have a new set of CATS I want to put on the car however I friend told me once putting CATS on it can cause damage to either the CATS or valves or something of that nature so I have held off. Sadly the car has sat over a year and I want to drive it in the beautiful Colorado weather as of late so want to put them on the car which will hopefully resolve the fume smell.. Can this hurt anything? Thanks for your input.
Yes, the cats will overheat and set the surrounding components on fire. You'll have to get the AFR ratio up to a more reasonable value (just slightly below stoichiometric 14.7:1) before you can install the cats. You can't take a car running at ~12:1 AFR and just put cats on it (although it will run very well at 12:1 AFR).
Has your car always smelled of gas,or did it begin at some point? Uncatted cars smell of gas,which is normal to those of us who grew up with such cars. If it is truly running too rich (fouling plugs?),the excess HC will ruin cats,so the rich problem needs to be fixed before adding cats.
You have no documentation about how to program/change its operation? You might have a Shop make a tailpipe %CO or AFR measurement to get a feel for where you are now. PS How are you getting by emission testing in Colorado? You register it in Texas?
Only what I downloaded from their website and I have a DOS computer for it, but its honestly above my skill level.
Steve, emissions testing is only required along the Front Range, which is Fort Collins in the north, Denver in the middle and CO Springs in the south. The whole rest of the state is exempt. The OP said he lives at 7000 feet so he's outside the emissions testing area. Sent from my moto g(6) play using FerrariChat.com mobile app
Have you inquired at Scuderia Rampante? If anyone can get your car straightened out, it's Dave Helms. Sent from my moto g(6) play using FerrariChat.com mobile app
Wow, that surprises me some -- I thought with Polis in the Governor's Mansion, CO would now be full-on CA Leftard everywhere.
Were getting close,, trust me! Thankfully El Paso county is pretty conservative and pushes back... Not to get into politics ;-)
Motec is perhaps the best aftermarket system available. Infinitely tunable. The trouble is execution. Something is wrong with the recipe. You must figure out the over fueling issue.
hmmm so I have heard, this one is a Motec M48 An older version which requires an outdated interface (according to the few mechanics I have spoken too)
Does you Motec have a provision for an oxygen sensor? If so, the self-tuning feature should adjust the A/F ratio. Install the oxygen sensor before installing the cats. In fact, the oxygen sensor just might solve your problem without the need for the cats. One final though, did you engine have an airpump? If it was disconnected or removed, it would be wise to put it back into operation. A rich A/F ratio need less gas and more air to return to the normal range. If you need to manually program the Motec, you need to find an experienced expert.
A critical question is whether anything is actually wrong. Did the gas smell start at some point,or has it always been there throughout your catless ownership? If the plugs burn clean and the engine runs fine,there is probably nothing wrong. On weekends I encounter street rods and restored classics. They smell of gas because they don't have cats to sanitize the exhaust. They smell of gas even when parked because they don't have evap systems. I built this about 35 years ago. A friend owns it now and is getting it ready for summer driving. It smells of HC and always has.
Yeah I need to find someone experienced with this set up. I don't believe this early version will self tune. Based on my research. But could be wrong
The M48 requires a dongle that was supplied by Motec inorder to communicate with the ECU. If you do not have that..you will not be able to talk to it. Contact Motec directly..and they should be able to help you. That is if they even service that particular unit anymore. The software used to be a free down load from thier site..it been a long while since I messed with one of these..
This probably isn't your issue, but these old Ferrari's vent their gas tank to atmosphere, thus causing a horrible gas smell, especially in your garage when your vehicle sits there for extended periods of time. I've put the following charcoal canister on a customer's 330 GTC, and that removed all gasoline smell from his garage which he was thankful for. We used the 8 inch version of the following filter: https://www.classicperformancerestoration.com/product-page/gas-tank-vent-charcoal-canister-fits-all-vehicles-with-a-fuel-tank Works very well, high quality materials used to make it from what I can tell. Good luck my friend!
If reprogramming the ECU is not practical, then you might want to use one of two tricks we used on race cars before. Bypass the intake air senor (you probably only going to be driving between 40 and 80 degrees anyway) and insert a resistor. Electromotive actually had a little switch at one time that accomplished that with up to plus or minus 10% fuel. Probably the IAT is a GM sensor. You can vary the resistance into change the mixture. I ran a wideband in the car, and was able to monitor. I used this at High Plains and Pueblo.....they are probably at 5500 feet or so. We dynoed the car in Dallas and of course even with a Map sensor it was never correct at altitude. If the car has a variable fuel pressure regulator, simply adjust this for less pressure. If not install one. This should be effective also. If the fuel pressure regulator had a vacuum port, be sure it is hooked up it will reduce fuel pressure at idle. With either solution, you want to confirm with a WB or on a dyno before you run under full load. I spent the last couple weeks in Keystone and yea the air up there is pretty thin. I am contemplating taking my carburated car there. I don't think I can find a dyno at over Denver altitude, but that should get me in the ballpark. Most of these early Motec systems were done I think by Norwood. You could contact him for a new file, but you would still have to deal with uploading a file.
