AUGieDogie

iTrader: (4)

OK so I was looking for someone out there who DOES NOT have a hot start issue with there FC. A good strong compression would help too.

I would like to know what your injector pulses are on hot start up. I have discovered (with hailers help) that if my injectors are pulsing at 20ms on hot start up it wont start. if i hit my switch and disable the wire going to pin 3b on the ecu my pulses go to 8ms and it starts right up.

Basically im trying to see if really is the compression that is causing it to flood on start, or if it is electrical.

Thanks
Augie

Henrik

That's very interesting. Pin 3b is the starter switch input to the ECU, if rpm's are low and this input is low, then the ECU will fire the primaries based only on the coolant temp sensor reading. 20ms corresponds to a sensor reading of about 53*C (127*F). Normal for a fully warmed engine would be 180*F. Do you have a 2.0? If so, what does the coolant sensor read when you have this problem? I would see it as unlikely that your problem is compression related, mostly likely some issue with your coolant sensor or wiring to it based on your info above.

-Henrik

AUGieDogie

iTrader: (4)

Henrik

I do indeed have the 2.0 version.
The engine is fully warmed up, when i have this problem. The temperature reads about 180f. I figured it wasnt a compression problem quiteea while ago, but you know how it is on this board. Almost everyone says "you need a rebuild" right away with a hot start issue. I know the compression is still pretty good. And it starts up every time, first time (when hot) as long as 3B is cut. Now I'm just trying to figure out why its doing this. Oh and i verify that the starter box is not checked on the diagnostic screen when i do this, just to make sure.

You say that it is only supposed to go to that map at a lower temperature? That explains why if i let it sit for a while it will start just fine. Before i had the switch to 3b i used a fuel cut switch to start the car when hot. If i was inside for a while it it would cool down and start fine. It has had this problem for ever, but only recently have i been able to narrow it down.

So if im reading 180f then my temperature sensor for the coolent is reading fine. Any ideas what else my be triggering my ECU to use this map?

Thanks for your help, and I love my 2.0!

Augie

Henrik

Well here's my belief. Hot start problems are usually caused by too rich a mixture being injected during start. Your evidence is supporting that. Now too rich can of course be from two sources: too much fuel or too little air. Correct either to be within range and no problems, your currently correcting fuel but that is not necessarily the real problem. One possibility is a bad BAC valve or driver. Easy to test, when idling warm pull the connector to the BAC valve. If idle drops, then its working, if not there's a problem. One of the several ECUs I tested with had a bad BAC driver and it caused my car to always flood on hot-start. Fixed the ECU and all was well.

-Henrik

AUGieDogie

iTrader: (4)

But why would the ECU use a map for 127F when the temp is 180f? Out of curiosity what should my pulse width be at 180f? Are any other sensors used during hot start that could be causing this?

I see ALOT of people with hot start issues. Quite a few still have them even after they clean the injectors. If this is the actual reason they are having issues then fixing it will help out alot of FC owners.

HAILERS

Congratulations Augiedogie, on finding the use of pin 3B and Hot Starting. Your a rare breed. There's too many deadheads out there the have not a clue how things work, even when you jpg the chart showing how the Start system works.

I run pin 3B's wire thru a simple voltage switch that is triggered by the voltage from the water thermo sensor. That means I never have to manually switch anything off/on for Hot Starts. I think you must have read my thread on HOT START PROBLEMS.

By the way, if you had your BAC unbolted from the manifold, and someone held the key to START, you'd see the BAC go to full open as long as the key is to Start. Been there, done that. Mine BAC always does that and is fully functional.

Henrik

The values actually turn out quite similar. I haven't verified the attached, but it should be correct. I could change this curve if needed. How's you BAC valve?

-Henrik

HAILERS

I know I'm butting in where I was not asked. But here are two jpg of the pulse width. One with the 3B connected and one with it disconnected. Quite a differene in pulse width. Fairly Hot engine as seen with the temps shown.

AUGieDogie

iTrader: (4)

OK so i figured out that my BAC is not actually working. This fits with what Henrick was saying about the fuel/ air mixture. The ECU has a fried transistor. With it not clicking open for start its not getting enough air. I had to look up how to test transistors, but it is definatly damaged.

So any suggestions about fixing the transistor? I shouldn't be too hard to desolder and replace BUT is this something that the Rtec guys would/could fix for me?

HAILERS

This article about three quarters down the page. I've done this several years ago on a non turbo car. Bought the part from RS for less than three bucks.

IF you unbolt the BAC and then turn the key to ON with the electrical plug still on the BAC, and you touch the diaphram and it's vibrating, then the thing is not broken.

THIS ARTICLE: http://www.teamfc3s.org/info/articles/idle.html

AUGieDogie

iTrader: (4)

Yup thats the article i've been useing.

But it's definatly the transistor. I putt another ECU in there and tested the conection with the resistor accross it and i got all the proper readings. Unfortunatly I cant use that ECU to start the car because I'm using 720s all the way around.
Im going to hit radio shack today and just swap out the transistor.

Henrik

Cool. Sounds like your ok with soldering in a new part, if you need a transistor, I can mail you one - I got a couple of ECUs I'm using for parts. mail me at henrik @ pocketlogger . com

-Henrik

Henrik

butt away - more correct information is always good. The value fits well with the graph. In the case where 3B is disconnected, the ECU would just think the engine is running really slow. Fuel would be as a function of AFM, air temp, rpm, etc. as for normal running.

-Henrik

AUGieDogie

iTrader: (4)

OK so I installed the new transistor last night. I did a quick test on my spare BAC and the voltage read right when I did the AC voltage thing. But when i installed it on my installed BAC the transistor blew again. I'm pretty sure that conector for my BAC is screwed up. I would be willing to bet that the are shorting inside the connector itself. They are very loose, and will slip out quite easy.

I installed another transistor into the ECU (bought two just in case) and I am going to cut my harness and splice in some conectors so that there is no way that they can touch. Hopefully I can get it to work with my spare OFF of the engine. IF it blows again then Im guessing that i have a bad wire some place. Thats plan C.

Thanks for the parts offer. It states that in the thread I've been using that TIP121 Darlingtons should work. However, the article never really finishes up and is like 8 years old.

Hailers you mentioned that you replaced the transistor? Was it TIP121 from RS? Also since i will be testing my BAC off of the engine I should be able to see it vibrate. I HOPE

Now it is supposed to click open on startup correct. Does it click and stay open? If so how much? When i tested mine it only opened about 2mm (or so) not much at all. This was with 12v DC accross it.

I'll post results tommorow. Wish me luck.

HAILERS

HOLDING the key to START results in a opening of about the 2mm you mention. And it stays in that open position as long as the key is to START. Let go and it closes and vibrates.

If yours vibrates and goes approx 2mm to OPEN in START, then it's probably good.

I bought the transistors from RS and they were probably the ones mentioned in the article. It's been several YEARS and I easily forget. I'd bet money I bought the ones in the article.

The wires in the plug sometimes don't lock in and short together killing the transistor. Look for that and bare wires near the plug.

HAILERS

By the way, that 2mm IS full open. I think you know that, but just in case.

AUGieDogie

iTrader: (4)

Well, I got the BAC (spare one) to work. The wires were cracked and split under the loom covering and that is the likely point of the short. I trashed my BAC connector any way since it is really bad. Gota find a new one and splice in some wires past the bad spots. I might (emphasis on might) just route a whole new set of wires back to the ECU. My stock o2 doesnt work right now, so i was thinking about just routing that wire and the Bac plug back to the ecu so I know they are new and not shorting.

Anway, I'm kinda curious about the BAC holding at full open. It is only when the IGN is at start correct? This gets kinda funky on my car since my starter (ECU) wire is cut when I try and hot start it. So Does that mean that my BAC is not holding at full open? This all goes back to the start of my thread. The pulse width reads 20ms or so with the starter wire intact and 8ms or so with it cut (which also prevents the BAC going full hold open) and it starts perfectly with the lesser fuel. With the hight pulse width the BAC full open hold should get it more air and still help it start, but that doesnt seem to be the case. ARGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGG GGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGG GGGGGGGGG!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!


OK so it goes back to the question from a few posts back.....why is my pulse width so high on hot start???

AUGieDogie

iTrader: (4)

OK so after a small test session today.

1. My water temp switch never comes on. I'm using the diagnostic screen for this.
2 with starter wire conected i get 14ms at 189F
3. It WILL start after about 3-4 secs of turning over but i can tell that it is just barely firing.
4. If it doesn't start after about 5 secs of cracking it wont start with out cuting the start wire.


Is the water temperature switch involved in the start up proceedure. I'm going to test it on monday and see if its dead. I'm wondering if this is whats doing it.

Again thanks for your help guys.

AUGieDogie

iTrader: (4)

quick question. Should my temp switch show an X when the switch shows continiuty?

Henrik

The pulsewidths are normal for a hot start.
Did fixing the BAD help at all?
The water temp switch is not used in start-up. The logger should show an X when the switch shows continuity which would be above ~62deg F. (probably hard to get below that temp about now).

-Henrik

AUGieDogie

iTrader: (4)

Herick, again thanks for all your help. My temp switch IS busted, but it reads continuity all the time so it will be fine for several more months. HOWEVER my check box on the diognostic screen is backwards. It never comes on. If i pull the plugs on the temp switch THEN the X is in the box. If i jumper the two wires that plug in the X goes away again. So its X for no cont. no X for cont. Backwards right?

OK so my pulse width is normal. Im going to examin some more systems and adjust my timing as its off a bit. I may just end up leaving the switch in as a "choke" switch for when the car is cold.


Thanks

Augie

Henrik

hmm, that's very curious - that is backwards from what I see with my test board. What version logger SW are you running? btw, did fixing the BAC output make any difference?

-Henrik

AUGieDogie

iTrader: (4)

Version number is 1.006.

The Bac is working like a champ now. Just that dead transistor. But no, the problem is exactly the same as it has always been.

I'm wondering, is there a way that you could program the rtek to switch the starter imput off at a certain coolant temp?? Might be nice little feature for some of use with hot start issues. The flood kill function really doesnt help with this particular problem.

Augie

Henrik

Yes, that can be done. What temp?

AUGieDogie

iTrader: (4)

HMMM Maybe slider or a choice of say 140,160,180 and of course have an on/off check box so people with "normal" starts can turn it off.
Hailers you have any input??

You figure out why im backwards on my temp switch?

and of course

Henrik you are the man!