14 replies to this topic

[Ian Hardaker]

I have a 1994 SPI that is not getting up to temperature. I check it with Mems Diag, and it is only getting up to about 85 degrees. It does not go into closed loop, and I'm not sure if the Lambda sensor is working because it always reads 435, but with it not getting up to 88 degrees, I don't know if the Lambda sensor has kicked in yet?

I put a new 88 degree thermostat in, and have just changed it to a 91 degree to try to get the temp up, but it's not happening. The coolant temperature sensor in the intake manifold was only showing 65 degrees, so I replaced it last weekend, and cleaned the contacts etc, now showing 85 degrees.

The radiator is a new twin core aluminium one  (from Ebay). Could this be cooling too well?

[DeadSquare]

If you think the rad is working too well, try blanking off 1/3 of the rad

[Ian Hardaker]

Thanks for the suggestion, I stuck a piece of cardboard behind it, but it's on the exit side of the radiator, so it doesn't do much good. Hard to blank off the fan side with the shroud and fan there! 

[Ian Hardaker]

I should also add that the water pump is a new high output one.

Also could I have the intake manifold piped up incorrectly, and does it make any difference? Where does the hose from the thermostat go? To the top or bottom pipe on the manifold?

[MatthewsDad]

Have you flushed the inlet manifold? Crud could be blocking the sensor and giving a false reading. You can also use an infrared thermometer, if you have access to one, to validate the readings you're getting.

[Ian Hardaker]

Yes I flushed the inlet manifold, it didn't seem too bad. Just tried blocking off the grill, still showing 85 on mems_diag.

[Pops_Guild]

I would think this was an issue with the inlet manifold temp transmitter. As mentioned above they get gunged up and/or fail. Difficult to get to and replace without taking the manifold off though ?

[Ian Hardaker]

It's a brand new temperature sensor in the inlet manifold. The old one was duff, so I replaced it last week and cleaned out the manifold. Much better, but still only 85 degrees. Where should it feed from the thermostat housing? To the top or bottom pipe on the manifold?

[tmsmini]

Just because you have an 88 or 92  thermostat, does not mean the engine will run at that temp.

Typically it means that the thermostat is fully open at 88, but starts to open earlier than this. And when the temp drops below 88, it is still partially open.

[xrocketengineer]

According to page 5 of this the operating temperature should be 80 to 100 degrees Centigrade. The O2 sensor could be failed.

 

 http://workshopmanua...pdf/read?page=5

Edited by xrocketengineer, 16 March 2020 - 12:58 AM.

[tmsmini]

I stand corrected on the opening temp assuming todays thermostsats are made to the original specification.
This is from the AKM7169 manual:

[tmsmini]

Interesting that there are different operating temperature ranges for SPi and MPi

 

Edited by tmsmini, 16 March 2020 - 11:11 PM.

[viz139]

I found before that my PTC connection had come off and the temperature never came up to normal. Recently I replaced my PTC and the car heats up much quicker. Might be worth investigating.

[Ian Hardaker]

Thanks for all the advice guys! I was under the impression that the Lambda sensor does not read anything, and the engine doesn't operate in closed loop until the temperature reads 88 degrees. I have a new Lambda sensor coming on Thursday, so hopefully that will start working and go into closed loop.

Still don't know about the coolant line connections to the inlet manifold... which one goes to the top pipe?

Viz139... What's a PTC?

Thanks!

[Ian Hardaker]

Viz139... I've searched and found what the PTC is!  Thanks...  and I do think it's knackered!