I am in the process of diagnosing the hot start system, it looks like I may have a problem already.

The FSM says that there should be no vacuum being pulled at the FPR for 90 seconds after startup.. Mine seems to be pulling vacuum immediately.

So it says test the "pressure regulator control solenoid valve" I cant seem to figure out if thats the orange one or the grey one...

Anyone know?

Jarrett.

 

Why you gotta as a real question? Blah.

Anyway, if you've got a Haynes, it's pretty clear. I'd look, but I don't have mine handy, sorry. It's the one called the "PRC" valve.

If I may, why are you testing this?

Brandon

 

****!! Why didnt I thing about looking in the Haynes!

Well, I am getting ready to sell the car, and it was having problems starting when it was warm.. So I checked the injectors, and they were leaking like champs. So I replaced them. Now I went for a drive, and its still having problems on startup when hot. AND YES I CHECKED COMPRESSION!! So I am assuming that there may be a problem in the BAC area. Or one of the Vac soleniods are malfunctioning. But when I tested them, I could hear them clicking.

So I just figured that I would do some tests. COurse I need to look at the IAT sensor too. I dont have a 2-3 kOhm resistor handy. So that may be negating the test results. I just figured that if the car was warm, it would be an equivalant.

Back to the drawing board..

Thanks!

Jarrett.

 

Orange ....and I thought it was fifty seconds on HOT start up on a series four. Gives higher fuel pressure for that small period of time.

 

If it's a series 4 car, I'd check the thermosensor on the thermostat housing. That's responsible for cold idle enrichment, and if it fails "cold" it could cause that problem.

Brandon

 

FSM says 90 seconds... And I thought that without the Vacuum, it LOWERED the fuel rail pressure, not raised it...

 

90 seconds it is. No. More atmospheric pressure equals higher fuel pressure. Put a fuel pressure gauge inline, then put a source of pressure on the fuel pressure regulator. As you increase the air pressure on the fpr, you will see the fuel pressure rise. On either a turbo or a n/a, if you in crease the air pressure to around 10psi, you will see the fuel pressure rise all the way to fifty psi plus. Been there, done that, both on a n/a and turbo.

I've driven the turbo car at boost of ten psi, and seen the fuel pressure gauge that I had inline, go to fifty psi. CAn't do that on my n/a(no boost). Had to use a mittyvac to dupe that on the n/a.

Darn. Wonder where I got the fifty seconds. Oh well.

EDIT: The fifty seconds came from the checkout of the fuel pump on a turboii. 12v for fifty seconds on startup and then down to the nine volts.

 

Okay, the FSM specifies without the vacuum, rail pressure should be 34-39 PSI, and with vacuum, 28.4 at idle... That makes HAILERS right (I hate that...)

So, I should not be pulling a vacuum on the FPR for 90 secs after a hot start.. the problem is, I am pulling vacuum...

I am going to get a 2-3 kOhm resistor tomorrow..

Jarrett.

 

K, I got a 2.2 kOhm 1/2 watt resistor from Radio Smack, so I am gonna try to see if the IAT is bad, or if its the vac relays.

Jarrett

 

ONCE UPON A TIME......There was a fellow named Akgeals(sp, maybe), who had a turboii. He had a problem with his BAC. It seems the BAC would click when 12v was applied but did not seem to work. He followed the instructions of Paul Stoakes, and found that the transistor in the ECU thats for the BAC, was fried. He soldered in a new transistor. WAlla. His BAC functioned.
As a side effect, he wrote and told us how he has no HOT START problem anymore. I think that is because on startup, the BAC goes wide open(I think I read that in the series five manual online, Fuel Section, towards the rear of that section).
Is it possible your BAC is not getting a input from the ECU????? Something to think about

Oh yes, ask me what I think about Radio Shack sometime. I really, really, really, really do not like a clerk hanging over my shoulder when picking up resistors, solder etc. Its like they are making sure I don't put anything in my pocket. I really need to write a letter to RS and tell them what I think about their store.. Yeah, I know he's on a commission. He misses out on any impulse buying I might do though.

 

Well, it just so happens that I have a spare ECU. So maybe its time to swap those buggers out, and see what happens.

The hot start system is mysteriously working now. With or without the 2-3 kOhm resistor.

Hmm...

Radio Shack? I hate that place... The clerks all think they know electronics, and take every opportunity to show you thier knowledge. I derive no greater pleasure then showing them up. Probably makes me a mean person, but I dont happen to care all that much.

My Kharma is already shot for the day..

Jarrett

 

i have a stock 87 T2 ECU i will trade ya for that starter..
Dave

 

This is for my N/A, but if that ECU is a 333, I will trade.

Rat

 

Well.....It did help my hot start problem considerably but it did not cure it. I DID fix my non-responsive BAC valve though. The damage to the ECU occured when the connector on the BAC broke and allowed the wires to short out on the manifold. All is well now....except the damn hot start issue (improved but not gone). I have check every sensor on the car! I replaced ALL the temperature sensors....even the ones that tested good, just in case. I had the injectors cleaned/rebuilt and did every thing else forum members told me to do. The car runs great, gets good mileage (for a TII), idles smoothly (even with the A/C on, thanks to the ECU fix), makes full boost and is a blast to drive. I don't THINK I have compression issues based on my last statement. Anyway....I cut my car off with the fuel pump switch and then I still have to restart (when hot and it sits for more than a few minutes) with the switch in the off position or it will not start. So....I wish someone could figure this out and tell ME what the problem is. The car always starts in under 2 sec. using the fuel pump switch but I'm going to want to sell her some day (when the RX8 is released) so I'd like to get it fixed if at all possible. I've heard that removing a check-valve in the fuel pump can cure this problem (although that's just treating the symptoms). Anybody have any ideas?

Todd