Looking for a car that has HOT START PROBLEMS
Joined: Mar 2001
Posts: 31,819
Likes: 3,223
From: https://www2.mazda.com/en/100th/
back from the dead...
I was thinking about this hot start problem recently. How many people have hot start problems, then completely replace their thermosensor with a brand new one and still have the problem?
When I was on stock ECU for my T2, I would have hot start problems. I would get to full operating temperature, stop the car somewhere and go to store for 15 minutes, then come back and it was flooded.
Interestingly enough, when I switched to a Power FC I immediately noticed that my water thermosensor was WAY off. It read too cold compared to my aftermarket gauge. It should have read around 90 Celcius (180ish degrees) and it would read 30! And if the ECU thinks the engine is still not warmed up, it will inject more fuel and potentially cause it to flood. I've also seen an inaccurate thermosensor on an FD. Has anyone else noticed inaccuracies on say their Rtek 2.0 ? Now the start maps are adjustable in a Power FC and I've never had any flooding problems since I switched to it. But that same inaccurate sensor was on my stock ECU.
How many people have put a brand new thermosensor in and still had these problems? Sorry if it was buried in this old thread and I missed it. I think a lot of times we talk about a thermosensor that is disconnected, or otherwise completely dead, but not many people recognize that the thermosensor can be fully hooked up and APPEAR to be working correctly and still be wrong.
The FSM has a voltage scale for the thermosensor but IMO it is not a precise enough to really tell you how correct it is without reading the ECU (through an Rtek or Power FC, or whatever else, and comparing it to another gauge). You can get a new thermosensor for like $40 at the dealer or even cheapr at a parts store. I think more people should go ahead and replace their thermosensor first to see if that helps, because it can be bad (inaccurate) but honestly you would never know.
EDIT: I looked back through the thread a little bit and there is some discussion of bad thermosensors. Let's just say I disagree that a bad thermosensor is easy to diagnose. I mean we can say it "should" be x volts under x conditions, but it's hard to know exactly how many degrees C the ECU is seeing if you are on a stock ECU with no datalogging capabilities. And even if it's "only" off a few degrees, that could potentially make a significant difference in how much cranking fuel the engine gets.
I was thinking about this hot start problem recently. How many people have hot start problems, then completely replace their thermosensor with a brand new one and still have the problem?
When I was on stock ECU for my T2, I would have hot start problems. I would get to full operating temperature, stop the car somewhere and go to store for 15 minutes, then come back and it was flooded.
Interestingly enough, when I switched to a Power FC I immediately noticed that my water thermosensor was WAY off. It read too cold compared to my aftermarket gauge. It should have read around 90 Celcius (180ish degrees) and it would read 30! And if the ECU thinks the engine is still not warmed up, it will inject more fuel and potentially cause it to flood. I've also seen an inaccurate thermosensor on an FD. Has anyone else noticed inaccuracies on say their Rtek 2.0 ? Now the start maps are adjustable in a Power FC and I've never had any flooding problems since I switched to it. But that same inaccurate sensor was on my stock ECU.
How many people have put a brand new thermosensor in and still had these problems? Sorry if it was buried in this old thread and I missed it. I think a lot of times we talk about a thermosensor that is disconnected, or otherwise completely dead, but not many people recognize that the thermosensor can be fully hooked up and APPEAR to be working correctly and still be wrong.
The FSM has a voltage scale for the thermosensor but IMO it is not a precise enough to really tell you how correct it is without reading the ECU (through an Rtek or Power FC, or whatever else, and comparing it to another gauge). You can get a new thermosensor for like $40 at the dealer or even cheapr at a parts store. I think more people should go ahead and replace their thermosensor first to see if that helps, because it can be bad (inaccurate) but honestly you would never know.
EDIT: I looked back through the thread a little bit and there is some discussion of bad thermosensors. Let's just say I disagree that a bad thermosensor is easy to diagnose. I mean we can say it "should" be x volts under x conditions, but it's hard to know exactly how many degrees C the ECU is seeing if you are on a stock ECU with no datalogging capabilities. And even if it's "only" off a few degrees, that could potentially make a significant difference in how much cranking fuel the engine gets.
my S5 vert has a warm start problem, and the thermosensor is on the list, because the car is NOT flooding, so its either too lean, or the there's water seal problem or something
I found the switch needed to fix the hot flood. I guess I need to figure out the values sent from the thermo sender vs temp.... I cant log my fc yet to see the voltage from sensor vs. temp. for setting the switch.
Here is the switch.:
http://www.jaycar.com.au/productView...h&form=KEYWORD
Here is the switch.:
http://www.jaycar.com.au/productView...h&form=KEYWORD
Yea this is an old thread but its the one I kept coming back to during my search to fix my issue.
I searched and read and searched some more. Went over the FSM a dozen times, broke out a multimeter, you name it I did it.
But a series of problems led me here, my last issue of my three problems, first being FP relay to a bad smoking issue(capped nipple off the oil fill neck thus creating too much crankcase pressure)
Anyway a big thanks to mr Hailers. I now feel comfortable enough to drive this thing on the streets since buying it 2 weeks ago.
cody
I searched and read and searched some more. Went over the FSM a dozen times, broke out a multimeter, you name it I did it.
But a series of problems led me here, my last issue of my three problems, first being FP relay to a bad smoking issue(capped nipple off the oil fill neck thus creating too much crankcase pressure)
Anyway a big thanks to mr Hailers. I now feel comfortable enough to drive this thing on the streets since buying it 2 weeks ago.
cody
S13Koop:
I was wondering what the symptoms were for replacing the FP relay? I have Rtek 1.7 that the antiflood feature would not work on... Now I'm wondering if it could not cut the fuel because maybe I have a bad FP relay?
I have installed a hot start switch now so I'm good, but would rather have the Rtek work like it's supposed to....
Thanks
I was wondering what the symptoms were for replacing the FP relay? I have Rtek 1.7 that the antiflood feature would not work on... Now I'm wondering if it could not cut the fuel because maybe I have a bad FP relay?
I have installed a hot start switch now so I'm good, but would rather have the Rtek work like it's supposed to....
Thanks
Mine was simpler than I thought. Unbeknownst to me the FP relay clicks pretty loud when working. Wasn't until I found the Circuit Opening Relay under the dash unplugged. Obviously when i plugged it back it worked. But this is when The hot start issue began (I just got this car and have no previous experience with rx7's and their little issues). Checked thermosensor and had toasted plug and harness. Replaced sensor and plug. Still had issues. I still suspect IAT sensor but I wanted to try this threads idea and it worked. IAT sensor still on the way though.
Junior Member
Joined: May 2012
Posts: 8
Likes: 0
From: Westminster, CO
Just wanted to chime in and thank hailers for this awesome post! Clipped my 3b wire and haven't had any hot start issue since then! Will add a switch because the car does struggle to fire when cold but after that it fires after two cranks.
Rotary Freak
Joined: Jul 2008
Posts: 1,660
Likes: 2
From: FORT WORTH TEXAS
S13Koop:
I was wondering what the symptoms were for replacing the FP relay? I have Rtek 1.7 that the antiflood feature would not work on... Now I'm wondering if it could not cut the fuel because maybe I have a bad FP relay?
I have installed a hot start switch now so I'm good, but would rather have the Rtek work like it's supposed to....
Thanks
I was wondering what the symptoms were for replacing the FP relay? I have Rtek 1.7 that the antiflood feature would not work on... Now I'm wondering if it could not cut the fuel because maybe I have a bad FP relay?
I have installed a hot start switch now so I'm good, but would rather have the Rtek work like it's supposed to....
Thanks
The RTEK , and I suspect also the stk Series Five, depends on the TPS signal to the ECU. With the TPS showing your foot is on the floor, AND that there is a START signal being sent to the ECU............is what matters for the anti flooding feature. Although I'm not that familiar with the RTEK 1.whateever, just the RTEK 2.0 and how the series five works to deflood.
I doubt very much if the IAT has much of anything at all to do with flooding/anti flooding.
Last time I looked the ECU looks for...........a START signal from the key being HELD to START....rpms under five hundred........the water thermo sensors input to the ECU.
A burnt up water thermos sensor would result in a default water thermosensor temp of 180* F......somewhat of a normal operating temp for a RX.
Also during any START event the ECU makes the BAC go full open and stay full open as long as the key is HELD to START. More air that way during starting.
Great post HAILERS2..Thanks for sharing this...
Joined: Sep 2005
Posts: 25,581
Likes: 136
From: Smiths Falls.(near Ottawa!.Mapquest IT!)
In his honor of his memory and his extreme dedication to this Forum I will lock this thread so his Name and remaining threads can go untarnished.
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