Robin 993DX

I am 100% positive it is not the starter.

AX993

+1, My '88 944S also has different temp sensors for the DME and the dash gauge.

cannik

To be exact, you mean replacing the starter motor fixed the problem of not able to start the car after a hot run? If so, any follow up issue ever since after the starter motor is replaced? and what is the cost of this unit? Thanks a tonne.

fast_freddy

No follow up issues. Fires up instantly every time. Cost? If memory serves it ran about $270 or so after I got my core deposit back. It wasn't too difficult to do either. I did have a bit of help and a lift which I'm sure made all the difference in the world.

Blaine S

Robin - here is another idea. On my E class there are two induction triggered position sensors. A crank position sensor and a cam position sensor. The fuel system will not flow until the proper signal from these sensors is sent to the ECU.

The classic problem with the E class is that it won't start after 20-30 minutes of driving on a hot day. Cold starts are no problem and if you let the car cool down after 20-30 minutes of driving they start again.

On the E class they are simple and easy to replace and cost about $150 ea.

Hope this helps.

- Blaine

Steve Weiner-Rennsport Systems

Robin,

Don't overlook the fuel,......................

Your ethanol-laden, CA-reforumulated gasolines are more susceptable to vapor lock issues in hot weather and cars with high underhood temps suffer accordingly.

Its a difficult problem to isolate and fix, but it IS possible to do so.

VNTGSPD

I was thinking fuel too. Costco and Chevron could use the same distributor. I'm not a distribution expert but I know there are far more gas stations and companies than there are refineries.

You could mix in some race gas and see if the symptoms change. The question is whether racing "pump" gas (i.e. Unocal 100) is still laden with the same ethanol - reformulation - junk? You might have to sample some race gas from a 55 gallon drum (VP) instead.

Robin 993DX

Guys, thanks for your input.

I am still suffering from the same issue so far no solution.

I have been told by others that it could be the crank position sensor, as it is same on the Ferrari the fuel pump does not turn until it detects a crank movement.

The ethanol in gas definitely is one area I can look into. I will try a different brand of gas next time and see.

BTW I have the same exact issue with my 996, never a starting issue until I got it really hot and parked it for couple hours, if I leave the engine cover open it never have an starting issue (same with the Ferrari). So I am sort of narrowing it down to a heat related issue. And I strictly uses Costco gas in my 996.

Here is a recap of the symptoms:

Cold start - About 2 seonds of cranking before engine will catch
Slghtly warmed up park for about 5-10 minutes - About 1 second of cranking before engine will catch
HOT, park for 10-20 minutes - about 3-4 seconds of cranking before engine catches

Slow Guy

I have a hard time seeing the starter causing this problem. Pretty much the only thing the starter is supposed to do is turn the engine over, if it's doing that and at pretty much the same speed as a cold or "hot crank" how would it be the starter?

I'm leaning towards the fuel and using the starter spray as mentioned earlier to verify.

Tippy

+1

Robin 993DX

So far no luck in fixing the hot starting problem, both the Ferrari and the 996. Excessive long cranking before engine will catch.

I have tried Mobil, Shell gas so far made no difference.

BobbyT

Hi Robin,

"Cold start - About 2 seonds of cranking before engine will catch
Slghtly warmed up park for about 5-10 minutes - About 1 second of cranking before engine will catch
HOT, park for 10-20 minutes - about 3-4 seconds of cranking before engine catches"

I think this is one of three things:

1. Somehow the engine is losing fuel pressure in the injection system, fuel gets vaporized, and hence the engine needs excessive cranking to reestablish correct fuel pressure to make the injectors squirt. On earlier cars with CIS, this was caused by a bad fuel accumulator.

2. Electrical resistance increases with temperature, so the voltage drops a bit to the fuel pump, injection system, and starter, thus making starting slower when the engine has had a hot soak. Could be battery is failing or invisible corrosion on the battery terminals, including where the ground cable bolts to the car body. It seems to me that everything on the car works better with a new battery (even the radio plays better), so I just routinely replace the battery every three years.

3. One or more of the sensors for the FI system are failing, and the hot soak makes it/them weaker.

AX993

Hi Robin, I'm still loving my RSR's on my '96.

Just the fact you're having this problem on two different cars points to fuel IMHO. Here in the SE, I'm having problems finding any gas without ethanol in it (seems Shell is the only one here without the ethanol sticker on the pumps), and I'm guessing you don't have ANY choice in CA.

Maybe an excuse for a road trip out of state, running out the CA gas, and filling up with non-CA gas ?

Robin 993DX

Everyone on the Ferrari side also said it is fuel turned into vapor. As the Ferrari's fule rail does not have a return, so anything that turns into vapor in the fuel rail will staill maintain fuel pressure but will require extra cranks before the engine will catch.

Several Ferrari spiders have reported the same issue since the spider's engine bay does not vent heat as well as the coupe. So it retains a lot of heat....

Glenn, glad to hear that you are still enjoying the RSR muffler. Thanks for the update.

FWIW, recently I just did a yearly fluid service on the Ferrari, engine oil, gear oil, brake fluids. It is not bad at all, very simliar to the complex level of a 993. However the factory shop manual is CRAP! wrong torque values etc....

Robin 993DX

I think I may found the answer to the 996 long cranking hard starting issue when hot.

While doing the 90k mile service last weekend I removed all the under panels to look for the fuel filter (location according to the shop manual) without any luck. Later I found the fuel filter tucked in the left side of the engine bay behind the coolant reservoir. (Must be a C4 thing)

The engine bay gets very hot, I am sure it is not good for the fuel that's in the fuel filter. Probably doesn't help with the high concentration of ethanol in California gas either.

I will try to experiement by attaching some aluminum cooling fins on the fuel fitler body see if I see any improvements.

Still a mystery with the Ferrari.