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Discussion Starter · #1 ·
Ok, the 91 turbo car is getting the AEM EMS installed so I am daily driving the 85 20v now. I have noticed that the engine takes quite a while to "warm up". I have the hoses ran correctly (at least I think I do). I don't know where to start. Could it be the T-stat stuck open? After running for awhile it will eventually warm up but never gets past a little above the 1/3.

I do plan to check my timing tomorrow also. I know I am running WAY rich because this thing pops and backfires more than my 16v ever did. I think it has something to do with the 20v afm. I think it was tampered with before. Is there a way I can check it to see if it is out of spec?

I am also using an absurd amount of fuel. I mean I used approx 1/2 tank in like 50 miles. This is probably due to the rich condition though. Anything else it could be? Like maybe the ecu still thinking it is in "warmup" mode? It will idle correctly but still won't show warm on the gauge.
 

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Make sure that you have the right temp thermostat
fitted 195 F ????
I fitted a 180F (80C) and started to use more fuel
if you are running cold the ECU will add more fuel and holed back the
timing till you reach the correct temp.
with the lower temp 80C and a after market SW20
muffler I picked up a extra 10 hp and 21 ftp
ps I cut the center of the cam cover out and had it welded back in the right way round so when the engine is viewed from the rear one can see the writing the right way up. :thumbup
it's a BT not a ST
 

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Discussion Starter · #3 ·
I will replace the t-stat and verify I have the radiator hoses ran correctly (the fill neck one goes to the t-stat housing correct?) I have bled the coolant at least 4 times thinking that is what it was to no avail. I know the engine is getting warm but not sure how warm as the gauge shows full cold, but the engine is hot. :)

Today I plan to replace the t-stat, spark plugs, tinker with the AFM, and see where we are after all that.
 

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sounds exactly like all symptoms i've seen when the t-stat was stuck open on mine. all the extra fuel is due to the engine never getting warmed up. i'd say 99% sure thats your only prob.

i've heard of quite a few people having issues with t-stats sticking on imported motors. seems to be quite common.

oh, and if the gunk that seals the top of the afm shut looks original and nice, definately don't mess with it. easier to never touch those things. especially with 20v ones being kinda hard to come by a spare. (plus i don't think there's anything wrong with yours) i won't hold ya back from the spark plugs tho, if you've never changed them. i'm a big fan of keeping ignition components up to date.
 

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Did you ever get your o2 sensor hooked up? If so, it could be the mitsubishi sensor you wanted to use is not quite right.

Running without the o2 (or an o2 that is sending a higher voltage signal) will make a difference in gas mileage. That plus a thermostat that is stuck open, and possible timing issues (bad poping and cracking) can send the fuel economy into the toilet.

Remember, the 16v uses that cold start injector circuit when cold starting. I believe it is on a timer, so it will eventually switch into normal mode despite what the actual engine temperature is. The 20v ecu controls cold start enrichment and is totally reliant on that engine temperature sensor. If the actual coolant temp never warms to normal, cold start enrichment never stops. Plus, vvt probably won't engage until after cold start enrichment.

I bought my 16v 87 with one of those cooler running thermostats and the engine never did seem to ever warm up in the winter. I didn't run into major running rich problems (timer switch), but I did get way more carbon residue.

Sounds like the thermostat is 80% of the problem and o2 and timing another 20%, though your timing might be just fine.
 

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Discussion Starter · #6 ·
I am definatley going to replace the t-stat and plugs. The reason I ask about the AFM is because it was NOT nice and stock looking. I had to actually put more rtv to seal it properly. I have been running the o2 sensor but can easily unplug it too.

And I am also having a problem finding a 195 degree t-stat. I can order a 192 degree one but will a 180 do for now?
 

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I can confirm, thanks to my little light, that VVT doesn't engage until the motor is at about 1/3 on the gauge. If I time it right I can floor it before it's warm enough and halfway through the gear VVT will suddenly kick on :)

I'll just echo what people have said, replace your thermostat with a genuine Toyota. Check your coolant temp sensor while you're in there for proper readouts. Both the 16v thermostat and the 16v coolant temp sensor work on the 20v.

Also, you can hook your coolant lines and your heater lines up either way really, and the car will still cool properly.
 

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Discussion Starter · #14 ·
I just bought the 180 degree STOCK 16v t-stat and am going to install it once I get finished with the engine swap in my customers 87. If it is the sensor I can get one off one of my parts engines (after I test it of course).

kanedom: I think everyone in this thread thus far has a silvertop. :) But thanks for the info.
 

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I consider it an investment. I'm about to start my third 20v conversion harness and see a good bit of demand for it. So far i've done about 1 a month.

The 2zzge has more to offer than the 20v. With the 2zz in a mk1, you are looking at elise type performance.

The swap has a few more hurdles though.

1. You will need to mod or fab an engine mount.

2. You will have to mod the exhaust header to point in the right direction. I have seen an off the shelf corolla header that looks promising though.

3. You will have to add the returnless type pressure regulator to get the fuel pressure up to 50psi.

4. The wiring is probably absolutely disasterous. Making obd1 work with obd0 is bad enough. obd2 is super picky and seems to take over the whole car. Getting the stock ecu to work will be tough, but doable I think.

I want to offer the conversion harness to make this swap easy, like the 20v.
 

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kameleon said:
Ok, the 91 turbo car is getting the AEM EMS installed so I am daily driving the 85 20v now. I have noticed that the engine takes quite a while to "warm up". I have the hoses ran correctly (at least I think I do). I don't know where to start. Could it be the T-stat stuck open? After running for awhile it will eventually warm up but never gets past a little above the 1/3.

I do plan to check my timing tomorrow also. I know I am running WAY rich because this thing pops and backfires more than my 16v ever did. I think it has something to do with the 20v afm. I think it was tampered with before. Is there a way I can check it to see if it is out of spec?

I am also using an absurd amount of fuel. I mean I used approx 1/2 tank in like 50 miles. This is probably due to the rich condition though. Anything else it could be? Like maybe the ecu still thinking it is in "warmup" mode? It will idle correctly but still won't show warm on the gauge.

I have the exact same problem ... or at least I did. My harness burned up and I sprung a gas leak.

The thermostat was replaced and brand new ... o2 sensor working as far as I knew. New spark plugs too.

I drove down to florida and got consistently 20 MPG (150ish to the tank).

Also never warmed up past 1/3 of the guage.

Also backfired like crazy.

Then the harness lit on fire and I sprung a gas leak. I hope the last thing doesn't happen to you.
 
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