90-91 HO swap

i just swapped a 91 HO engine to a 90 non-HO xj. started it today, idles, but if i give it any gas it sputters and backfires badly. in the swap, i had to swap distributors. could i be one cog off in timng the dist? it ahs the 90 computer and harness, didnt swap any of that, just the sensors for the 90 comp. also, there is a sensor on the 90 radiator, i assume temp, what was that for? there is a temp sensor on the block, i assume for the computer. i swapped radiators also, and the 91 rad. does not have a sensor there.

thanks

Any time use swap a distributor you risk installing it off a tooth, or 180 degrees off, that will make it backfire. The sensor in the block is for the ECU to determine fuel req., & the sensor in the radiator is for the electric fan. BTW, the sensor on the back of the intk man. is for the temp. guage. I think it'll run OK with the CPU sender, that's crucial.

BTW, the '91-up sensor is missing from the radiator because they relocated it to the water outlet housing.

if it was 180 degrees off would it run at all?

so the electric fan is controlled by coolant temp? for some reason i thought it was turned on for the ac syst. so i can just rewire the sensor on the therm. housing to the old plug for the rad. sensor?

yes, coolant temp determines on/off for the fan on the '90. I don't think you can just wire it up, i believe the sensor for the HO (in the t-stat housing) is different. Search, you'll find it. Check offroad.com, they have a HO swap page that addresses it. 180 degrees off, no I don't think it'll run, but it might sputter. I've never (thankfully) made that mistake, but I've heard of people getting a few coughs out of em.

ok, i'll have to check in to that sensor. i think i've got the dist a cog off, i'll have to try that. thanks a bunch for the info!