TBI or Carb?
 

hello everyone,

We'll be leaving for an overland trip from Turkey to Mongolia in two weeks, in 2 throttle body injected Lada Nivas. As nearly all the counties are ex-soviet, we don't expect much spare part issues (although we'll have plenty with us)

The cars are equipped with GM throttle body injection. Although most mechanics say we'll be fine with it, a friend that works on engine r&d told me that the cars shipped to Europe are software programmed for specific altitude ranges, and we may have issues in different altitudes (we'll drive on the Pamir highway, ranging from 2000meters to 4200). Also, different fuel quality may cause us problems with injection, ECU might not be able to compansate for ignition timing.

I'm wondering if we should switch the cars to carb for such a trip? What's the general opinion for GM TBI system?

thanks,

I don't know anything about the GM TBI system itself but in general fuel injection systems are better at dealing with changes in altitude than carbs. To adjust a carb for altitude use you need to swap out the main jets. On the carbs I've worked on on Ladas this is a doddle, we had a blocked jet on a lada Niva in TM that took 5 mins to fix.

Do you know what the specific model of TBI it is and what sensors it has? I know some of them use a MAP sensor that should help with making some adjustments on your behalf (the function of the MAP sensor is to calculate air density, so it's constantly adjusting for altitude and air temperature). GM also produced different versions of the PROM for low and high-altitude versions of some cars on the californian market. You might be able to get some 'high altitude' PROMs and swap them out when required.....

The diagnostic manual I have for niva 1.7 tbi says it is Model 700. I didn't check it with the stickers on ECU.

sensors:
1. Crankshaft position
2. Manifold absolute pressure
3. Coolant temperature
4. Throttle position
5. Octane adjust potentiometer
6. Oxygen sensor
7. Intake air temperature
8. Vehicle Speed

it doesn't have a knock sensor, so I'm concerned with low quality fuel as well as altitude problems

I'd say go with the EFI setup you have rather than switching to carbs then. I know nothing of whether or not you can change the ignition timing easily on that engine - might help with the knocking. Other than that if you are having a knocking problem you could add octane booster to your fuel or do the bodger fix of tape up some of your air filter to richen the mixture. It'll be 'richer' but weaker (less fuel and air in total) and your oxygen sensor might over-compensate for it....

Considering the origin of the vehicle I would think it very unlikely that it wont cope with any conditions encountered in the home country . From my experience EFI can handle a very large reange of fuels/ pressures etc . So as advised above stick with the TBI

As far as I learned, the injection system is exactly same with vauxhall / opel astra.

It seems like we will be starting the journey with TBI, if I don't get negative feedback on it. Even if it causes problems, I know its components better than a carb anyway (although I'm not sure my information might be useful in case of problems :) )