Hpf 2.5 falling into random rich mode. Help!

My 2.5 has been falling into an awful rich mode (11 at idle) and runs very poorly after it gets warmed up a bit and then usually goes back to normal (13.9 idle) after sitting for a couple hours. I have only had it 4 weeks and it seems to have gotten progressively worse. It would do it once and then not go into the mode for a week, now it seems like every day.
It is not o2 or map sensor and the plugs were changed by hpf before I bought it. I have a local shop looking at it but without being able to look at the timing and everything we can't figure it out yet. He has a call into Chris at hpf so hopefully he will be able to help. Any ideas?

Is it only rich at startup or does it get rich after driving around for a while? Do you have an aftermarket thermostat? The car will be rich during warmup until coolant temps reach normal temps.

It's fine at start up. The rich mode kicks in after driving around and normal engine temp is reached. And then it won't go away until the car cools down. Def temp. related. Thermostat should be stock.

Interesting indeed. Sounds similar to the problem Marcus was having but I dont think they ever figured it out. How many km's do you have on your setup? V2 or V1 EMS? Other mods? Did Chris ever post up your car on the forums? I've noticed ever since Mfest there has been a large reduction in postings of freshly built HPF cars...something I've always enjoyed.

Originally Posted by Commanderwiggin

Interesting indeed. Sounds similar to the problem Marcus was having but I dont think they ever figured it out. How many km's do you have on your setup? V2 or V1 EMS? Other mods? Did Chris ever post up your car on the forums? I've noticed ever since Mfest there has been a large reduction in postings of freshly built HPF cars...something I've always enjoyed.

I think he bought it used.

I could be WAY THE HELL WRONG HERE but I thought someone mentioned a symptom like this being related to TPS sensors.

My car just ran rich as a pig period.. didn't matter if it was warm/cold/etc... it was a rushed tune the day before MFest with plugs that were to cold. Likely easily fixable had I sent the EMS to HPF but I wound up going ProEFI so I didn't want to waste anyones time at HPF. But his sounds intermittent and I could have swore that the TPS sensors could cause that sort of behavior, especially if not all replaced at once.

I did by it used. I am the 3rd owner and the build has appx. 14k miles on it. It was a local portland car and hpf did all the normal maintenance on it. They also tested it thoroughly before the previous owner sold it to make sure everything was in order. It drives excellent when it does not slip into this mode. The only other engine mods are hpf cf intake, rogue el diablo exhaust, and earls oil cooler. Maybe its tps...
Thanks

Originally Posted by KCHPFM3

I did by it used. I am the 3rd owner and the build has appx. 14k miles on it. It was a local portland car and hpf did all the normal maintenance on it. They also tested it thoroughly before the previous owner sold it to make sure everything was in order. It drives excellent when it does not slip into this mode. The only other engine mods are hpf cf intake, rogue el diablo exhaust, and earls oil cooler. Maybe its tps...
Thanks

Before digging to deep I'd wait until tomorrow and see what the crew at HPF recommends. It could be something they've seen before.

Just an update that we haven't gotten a hold of tech at hpf yet...hopefully tomorrow.

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Hpf has a trouble shooting guide on their website. Check it out, answers a lot of questions.

Yes, thanks we have been looking at that and did some troubleshooting from it but were hoping to narrow it down a bit based on the symptoms.

Originally Posted by KCHPFM3

Yes, thanks we have been looking at that and did some troubleshooting from it but were hoping to narrow it down a bit based on the symptoms.

Did u ever solve this problem?

Yes, it ended up being the dual vanos that had gone bad. We replaced it with a refurbished one from Dr. Vanos and the cryo-sealed hub. Not cheap, but all is working well now!

My vanos is also gone, how much did you pay for the Dr's unit?

Rough cost estimate:

Vanos-$1200
Cryo sealed exhaust hub-$900
Labor-20 hrs appx.
New Cam bolts-$20

Not cheap but the results were great! I only purchased the hub as it was recommended for high horsepower cars.

Labor depends on who does it...5-8 is more realistic but the other figures are legit and the job requires special tools.

Mine has the same symptoms - pig rich at idle (10.1-10.5 AFR) and loss of torque at low rpm. On scanner I receive vanos errors...

First I thought the bolts where backing out, taken everything apart and found bolts where in original position - nothing moved. Then I noticed in the vanos unit that the small piston on the intake side is not sliding freely (like the exhaust one), it was randomly blocking... So new vanos unit is needed, I don't know if to buy it from DrVanos or to buy a second hand one.

I would think the Dr. Vanos would be best as they upgrade certain parts to make it more telltale. What's the cost difference?

Originally Posted by Cipri

Mine has the same symptoms - pig rich at idle (10.1-10.5 AFR) and loss of torque at low rpm. On scanner I receive vanos errors...

First I thought the bolts where backing out, taken everything apart and found bolts where in original position - nothing moved. Then I noticed in the vanos unit that the small piston on the intake side is not sliding freely (like the exhaust one), it was randomly blocking... So new vanos unit is needed, I don't know if to buy it from DrVanos or to buy a second hand one.

Bought all my vanos parts from Dr.Vanos after having countless issues with vanos and trying second hand parts to only end up with the same problem & new ones. Every new Dr.vanos piece I put my car would be back to normal until the next weakest link gave up. After basically replacing everything from Dr.vanos my car has been perfect ever since +1 for Dr.vanos

A second hand vanos unit is 350$ here local, I don't have to pay for labour because I can make the swap, already changed the vanos bolts by myself.
I think I will wait until spring when building the engine and see what remaining budget I have.

Originally Posted by Cipri

Mine has the same symptoms - pig rich at idle (10.1-10.5 AFR) and loss of torque at low rpm. On scanner I receive vanos errors...

First I thought the bolts where backing out, taken everything apart and found bolts where in original position - nothing moved. Then I noticed in the vanos unit that the small piston on the intake side is not sliding freely (like the exhaust one), it was randomly blocking... So new vanos unit is needed, I don't know if to buy it from DrVanos or to buy a second hand one.

glad u went used...
pm sent