gunnerthesnowman Posted June 9, 2011 Report Share Posted June 9, 2011 Hi , i have a V88 installed on my turbo charge sled , the engine coolant normaly runs around 45-50c (internal termostate bypass ) so the tunner had the warm up enrichment table set at all 0 at 40C ECT , the fuel table was mapped with the set up this way , problem is in warmer weather or higher engine loads the ECT rises to 80C before the thermostate opens for more cooling , tune goes really rich due to the higher ECT. I have found a Warm up enrichment table on here that Ray has posted , My ? is , do i install this table and retune the engine with the new warm up enrichment table active with the ECT at 45-50C Thanks Quote Link to comment Share on other sites More sharing options...
rayhall Posted June 9, 2011 Report Share Posted June 9, 2011 If the warmup enrichment table has zero above 40 deg C, then this table has no effect above this temperature. The air temp fuel correction table would be the thing that is causing the AFR to not be correct at higher temperatures. When you tune the engine, you get the engine up to temperature and then look at the air temperature. This value is then used as the zero correction point in the IAT table. The values at lower and higher temps are put into the table so the number are negative above the zero point and positive below. Tipical table settings. Quote Link to comment Share on other sites More sharing options...
gunnerthesnowman Posted June 9, 2011 Author Report Share Posted June 9, 2011 All i am asking is , should,nt the warm up enrichment map be in affect ( no 0 in table ) until the engine is up to full operating temp.(80C) , with it being set to 0 at 40C , then there is no fuel correction from 40C to 80C , looking at the warm up enrichment table that you have posted on here , it is still adding over 20% fuel at 40C , by the time the ECT is up to 80C , the warm up enrichment is 0!! Quote Link to comment Share on other sites More sharing options...
rayhall Posted June 9, 2011 Report Share Posted June 9, 2011 I did not ignore or misunderstand your question. My answer was correct. The engine water temperature does have an effect on the air going into the cylinder. The port, valve and cylinder do have an effect on the density of the air. Any change in density effects air fuel ratio. To adjust for the temperature of the air in the cylinder, the ECU uses two values. Engine coolant temperature and air temperature. As it is the air temperature that effects the density the air temp sensor is the one that is used for most of the correction. The ECT tells the ECU the temperature of the water in the engine. This can have very little relation to the air temperature. Example:- I drive my car to work on a cold morning and the ECT is 90 deg and the air temperature in the manifold is only 28 deg. In summer the ECT is 90 deg and the air temp is 50 deg. Basing fuel correction for air density on ECT would not work, it needs to be on IAT. This is why the ECT Warmup table is not your problem. It is the IAT table. Any boat using raw water has a ECT warmup table that ends at 40 deg C. Very common solution for engine that run cool water temps. The IAT is used to correct for higher air temperatures. Ray. Quote Link to comment Share on other sites More sharing options...
gunnerthesnowman Posted June 10, 2011 Author Report Share Posted June 10, 2011 Yes , i understand what you are saying and do not think that you were/are ignoring my Question , If your warm up enrichment table ends ( all 0 ) at 40 deg. , what happens if you drive your car to work with a ECT of 40 deg and IAT of 20 deg. , then drive it to work with a ECT of 90 deg and IAT of still 20 deg.,!!! Quote Link to comment Share on other sites More sharing options...
rayhall Posted June 10, 2011 Report Share Posted June 10, 2011 what happens if you drive your car to work with a ECT of 40 deg and IAT of 20 deg. , then drive it to work with a ECT of 90 deg and IAT of still 20 deg.,!!! If the IAT is 20 deg with the engine at 90 deg, then it is not possible for it to also be 20 deg at 40 degrees. The IAT will be lower and the IAT fuel correction will adjust for the different air density. I think, you think the ECT is what the ECU uses to correct for air density changes. This is not really the case. The engine coolant temperature is the temperature of the intake ports, inlet valves and the walls of the cylinder and head. It is not the temperature of the air when it gets into the cylinder. The heat radiated from these items does heat the air, but it is not the actual temperature. Also the higher the engine speed the less these items effect the air temperature in the cylinder. So a engine at WOT at 40 deg C and another at WOT at 90 deg C will have much the same radiated heat from the ports, values and cylinder walls. The IAT when mounted in the intake manifold will give a much more accurate indication of the air temp when it gets into the cylinder. This is why the IAT fuel correction table is critical on keeping the AFR correct under all conditions. The ECT warmup table is used to assist the with the correction when the engine first starts. Ray. Quote Link to comment Share on other sites More sharing options...
rayhall Posted June 10, 2011 Report Share Posted June 10, 2011 In another life...The ECU had a fuel correction table based on the percentage the engine hardware effected the air in the cylinder. This is a better method, but still needed some work to get correct. Downside was you had no control over the effect the IAT had on the final calculation of injector time. Ray. Quote Link to comment Share on other sites More sharing options...
gunnerthesnowman Posted June 10, 2011 Author Report Share Posted June 10, 2011 If the IAT is 20 deg with the engine at 90 deg, then it is not possible for it to also be 20 deg at 40 degrees. The IAT will be lower and the IAT fuel correction will adjust for the different air density. I think, you think the ECT is what the ECU uses to correct for air density changes. This is not really the case. The engine coolant temperature is the temperature of the intake ports, inlet valves and the walls of the cylinder and head. It is not the temperature of the air when it gets into the cylinder. The heat radiated from these items does heat the air, but it is not the actual temperature. Also the higher the engine speed the less these items effect the air temperature in the cylinder. So a engine at WOT at 40 deg C and another at WOT at 90 deg C will have much the same radiated heat from the ports, values and cylinder walls. The IAT when mounted in the intake manifold will give a much more accurate indication of the air temp when it gets into the cylinder. This is why the IAT fuel correction table is critical on keeping the AFR correct under all conditions. The ECT warmup table is used to assist the with the correction when the engine first starts. Ray.[/quot No i do not think that the ECT is what adjust for the air inlet density , from what i have read in the vipec "whats this" the warn up enrichment works off of ECT to add fuel to get the correct AFR when the engine is below normal operating temp.(90deg.) because of fuel condensing on cooler cylinder walls, piston top etc , , so by the time the engine reaches operating temp. (90) the warm up enrichment has pull fuel to keep the right AFR.at normal operating temp. And yes it is possible to have the same IAT (20deg.) {My IAT senser is after the intercooler before the butterflys to the engine } At ECT of 40deg OR 90deg. On a sled , the coolant is cooled in tunnel heat exchangers , when i am riding in deep powder , the snow from the track going up on the exchanger keeps the coolant at 40-45deg ( there is a bypass around the 80deg. set thermostat) so IAT is 20deg and ECT is 40deg. Now , on the same day the IAT is 20deg. and i drive the sled down a hard pack trail , no snow going up onto the exchangers and the engine coolant temp will rise until the thermostat opens (80-90deg.) for more cooling , so IAT 20deg. and ECT 90deg.!! Quote Link to comment Share on other sites More sharing options...
rayhall Posted June 10, 2011 Report Share Posted June 10, 2011 Unfortunately I did not write the help in the manual. It was written by a software programmer. I have constantly battled people mapping engines not using the features that were put into the Vipec, to make it easy to tune and not be like other make ECU. The help is full of Link mapping methods. None of them should be there, as the Vipec was my ECU. I have given you an example of why engine temperature does not have a big effect on air temperature when the engine is at WOT, and the IAT table is used to correct for changes in air temp. Mounting the IAT as close as you can get to the cylinder the more accurate it will be. Ray. Quote Link to comment Share on other sites More sharing options...
gunnerthesnowman Posted June 10, 2011 Author Report Share Posted June 10, 2011 Did not know that you did not agree with the help link manual in the vipec software program , the problem i am having is not at WOT , it at idle and low end ( say 50-60% ), my last tuner had it set up with a warm up enrichment table that looked like the one you have posted on here and i was not having this problem , from the warm up enrichment table that you posted up here (http://www.vi-pec.com/bin/StartUpSettings.png)it pulls over 20% fuel from 40deg. to 90deg. ECT on low end (50-60%), I guess i am not understanding way the table you posted is set up this way when you are saying the ECT has very little to do with the engine fueling from 40 to 90 deg.. I hate to call it Quits on this standalone , but after 3 years and alot of money and two tuners and it is still not set up right i am at the end of my rope. Thanks Curtis Quote Link to comment Share on other sites More sharing options...
Guest |804| Posted June 10, 2011 Report Share Posted June 10, 2011 Seriously mate Ray has explained it clear as day for you. Use IAT for fuel corrections, make sure you have no ECT fuel corrections above 40 degrees. The link to the warm up enrich map that you posted isnt pulling fuel either, its adding fuel Find a Vipec accredited tuner and they will surely put you right with the tune, assuming you have taking to 2 tunners that dont no s#@t about Vipec :x Quote Link to comment Share on other sites More sharing options...
gunnerthesnowman Posted June 11, 2011 Author Report Share Posted June 11, 2011 Seriously , i do not know how i am going to use the IAT table for a fuel correction when the IAT is not changing , if you tuned the main fuel table for a good AFR when the engine is running at 40-45deg using the warm up enrichment map in the link , and then if the snow conditions changed and the engine warmed up to max operating temp . 80-90deg. ( thermostat opens ) the warm up table would be pulling fuel.?? Quote Link to comment Share on other sites More sharing options...
Guest Hic Posted June 13, 2011 Report Share Posted June 13, 2011 It is so easy to fix that, just a bit of imagination Setup 4D fuel table which will be activated with Virtual Aux1 as GP. Then, just make a table with axis: ECT and RPM/MAp/whatever you need. That is it. Add/SUbstract fuel where ever you want and however you want. 4D table will be activated with Virtual AUx as you set it up. That is it. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.