So, I just did an entire rebuild. Things looked pretty good after startup, good oil pressure, seemed to be ok, and I let it run for a bit. However, then the problems started. These all may or may not be related.

1. I have error codes 12 and 18. This is the Throttle Position Sensor. However it is hooked up just as it was before! what exactly will throw this code?

2. The car runs like crap as soon as you hit boost. It will buck like crazy, doesn't have any power, and is worst at low RPM. Higher RPM (above 6k) it will run smoothly but doesn't have any power.

3. The idle is around 500 and the car will actually die some times. Is this related?

4. It may or may not be missing every once and a while. I am not sure about this.

5. A much less important issue, I unplugged the smaller connector from CPU2 as my car currently thinks it is stolen. If it helps, my Viper locking system doesn't work either. This is low on the priority list, but if anyone has dealt with this before so I don't have to trace everything I would appreciate the advice.

Please help!

Thanks

 

So,

After looking through the manual, I think I have my throttle position sensor installed backwards (the connector towards the middle of the car). I plan on fixing this first thing in the morning.

Could this be my problem?

 

have you broken the engine in yet...?

 

No, the engine has only run about 20 minutes. What during break in would cause these symptoms?

When I say "sputters under boost", I mean that it runs poorly at 1 PSI at maybe 3000 RPM. I am not even trying to accelerate hard!

 

Fix the TPS then test again. Make sure you actually adjust it as well after you fix the installation:

http://www.fd3s.net/tps_adjustment.html

While that may be "a" problem, no one can tell you it's your only problem. Fix one thing at a time and keep moving forward.

 

I bet if you fix the TPS sensor, you will be fine

 

Well... better, but not fixed.

I had installed the TPS in the right direction it turns out (I think the drawing in the service manual is backwards), but I had totally not preloaded it meaning it wasn't moving at all. duh!

This fixed my idle (I am not at ~800 instead of 500 and dying) and cleared the error codes. It seems to run a little better at low RPM.

The bad news is that the boost problem is still there. It is super abrupt, as soon as I go a tiny bit positive on the intake pressure it starts running terribly. If I back off a little and it goes to vacuum again it runs fine again.

I still may sense it is missing slightly, but it is hard to tell. It also starts to make a slight opening and vibrating (vrooommmmm) sound when I rev slowly past 3000 rpm. I think this was there previously, but it has been 6 months since I drove this thing.

God, that TPS is incredibly hard to get to. I now know just to take stuff off and make it easy. It took me a good hour to get it off and on.

 

check map sensor connection+hose

 

Thats my guess too

 

So.

I checked the MAP hose (on the back left of the engine compartment, right?) and it appears to be 1, hooked up, and 2, has the gas filter going the right direction (the arrow towards the engine). I didn't have time to check the voltage before I had to leave to fly out, but why would the MAP all of a sudden decide to fail? It seems odd that it would only fail when under boost. I will check the voltage as well as where it is hooked up to when I get back in a few days.

Thanks for the suggestions so far.

 

Have you adjusted the TPS and made sure it's within spec?

Have you checked your codes to see if you are still throwing any?

Have you verified you have the connectors for the CAS on the appropriate sensors?

 

If the throttle wasn't adjusted, wouldn't it throw the check engine light again?

I am honestly not sure what CAS stands for. If you could enlighten me I will check the connections!

 

No. A misaligned TPS will not throw an error. You'll only get an error if there is an issue where the ECU cannot get the allowable values (i.e. disconnected or issue with the wiring between the sensor and ECU).

Crank Angle Sensors. They are the two sensors on the front cover behind the trigger wheel. The white connector goes on the top sensor, grey on the lower.

 

You are in limp mode. Check codes again. If it bucks and backfires as soon as you hit possitive pressure you are in limp
mode. Dud you go non-seq during the rebuild or delete any of the emissions?

 

No and no, at least not intentionally. I am 98% sure that all the emissions and turbo stuff is hooked up correctly. I had an intake leak before the throttle when I started the car up which was causing the turbo to spool, could this have done anything? I have an aftermarket boost controller (Blitz SBC i-color) which is actuating both the precontroller and the wastegate.

Could the fact that my car thinks it is stolen have anything to do with the limp mode? To get the car started I had to disconnect the CPU2 small connector. It didn't look like this had anything to do with running, but I could be wrong.

Importantly, if the car is in Limp mode, what exactly is it doing? Is it controlling boost by cutting spark or fuel? Is it safe to drive a little bit? Winter is going to hit VT hard soon, and I need to get the car 1 hour to my heated storage.

Mahjik, I will check both the TPS alignment and CASs when I get home. The TPS could be off as I only "put it where the wear marks were" and watched to see if the code stopped coming. I am pretty sure the CASs are hookd up correctly, but I will check.

Thanks, this has been very helpful so far.

 

Is the car bone stock? Nothing deleted/modded what so ever?

 

I suppose I should have started with this.

The car is really close to stock. It has the Blitz boost controller, a downpipe, and that is it. Nothing else in terms of modifications to the engine. It has a Fluidyne radiator, but I don't think that has any effect. I used to run 10 PSI of boost (and I still would be if the car was running), the boost controller was put on by a previous owner (and might have something to do with why I am doing this rebuild).

It has an aftermarket Viper security system which also currently doesn't work. I haven't tried looking at this, but I have the sneaking suspicion that it has something to do with why my car thinks it is stolen. Perhaps the battery being out for long periods of time caused this?

The car has misc. suspension upgrades, but those don't really matter.

 

An Update!

I had someone check the error codes while I am still away. No codes at all!

Still no update on the CAS and TPS adjustment, those will have to wait until I am at the car.

I didn't see any mention of the "Limp" mode in the service manual. Is this something that has been documented elsewhere in this forum? I did a search and couldn't find anything.

 

Ok, I finally got the time with the car to be able to test the TPS and CAS. The white connector is on the top CAS, which I believe is correct. The TPS was just just out of specification, with the high reading being slightly over 4.6 V. I adjusted it so that it was .38-4.55V, and 0.81V to 4.96V. If I adjusted the lower values up at all the higher narrow angle one got too hight, so I had to make it pretty tight.

While this *may* have helped the car idle a little better, it didn't fix my main problem. However, in testing, I have more information about the problem!

I still get "immediate stutter" whenever hitting boost under 4k. However, if I slowly rev to around there, and then roll on the throttle I can make boost briefly from 4-6k. However, around 5k it starts to drop off, and I am back down to atmospheric at 6k. I only took it to 6.5k, as I haven't fully broken the engine in. The boost seems to be immediate, but it is like the secondary isn't kicking in (or something else is going on).

Does this help at all? What else should I be testing/trying?

 

Guess you shouldn't be boosting at all while breaking in the engine IMO.

Besides that, start testing your seq turbo system... from leaks to a stuck wastegate....
Did you install new vacuum hoses?

 

All new vacuum hoses. I agree checking them is a good start. DJSeven seemed to think it was "limp mode" though, and I just can't seem to find any literature on this. If it is really a "shut down all turbo functions" it might also cut out opening the secondary intake control valve, maybe causing my boost problems.


It is hard to not boost at all when you are say, climbing a hill in 5th gear on a highway. I generally see 1-2PSI on the VT highways on hills. I guess I will either downshift or lose speed.

 

1-2 psi is ok... but your description suggests your doing more than that...
Does the car run normally on light throttle to 3-4k rpm? On a straight road that is...
Hard to tell if its a boost problem or not...

Since the vacuum hoses are new, did you install the restrictor pills were needed?

 

Next thing to check is your ignition. Make sure you have the harness wires going to the appropriate coils (i.e. correct color connectors), and then make sure you have the appropriate plug wires going to appropriate coils/plugs.

 

I didn't install the restrictor pills because I have a blitz SBC boost controller set up to actuate the pre-controller and wastegate. This was not changed from when I took the engine out.

The car runs normally so long as there is NO boost at all. As mentioned before, as soon as I hit +1 (or really anything above 0) PSI the car basically dies at low RPM.

I am only trying to test the boost to give people a better problem description.

 

My car did the same thing when I bought it. Thee guy who had it before me did the poor mans non sequential mod and deleted the rats nest. My guess would be to go to the rats nest and make sure everything is connected. Apparently you get thrown into limp mode if some are disconnected.