The 1989 Dodge Daytona Shelby Diary: Minus two ... plus three ... then minus one.

I've had my car in the shop the last few weeks to fix a pickup coil in the distributor, rebuild the AC from the dash forward (including going into the dash and replacing the evaporator core) and replace both a leaking oil sending unit and I'm guessing the oil line on the turbo (replaced the rubber hose part between two hard lines with a hard line). In that process, the mechanic had to go back in and replace a (brand new) bad expansion valve on the AC when the AC stopped working 20 minutes after I picked the Daytona up. When I got the car back, the radio and CD player / cigarette lighter / power port no longer worked. I'm thinking something got left unhooked under the dash (or a fuse) for the electronics part but that's not the bad part of the story, just background to catch you up.

I drove the Daytona today, runs fine, AC blows cold, no oil leaks. However, it starts to stumble a little going into boost with the AC on and it doesn't like more than half throttle let alone WOT with the AC on ... no, not at all. It falls flat on its face somewhere around 3500 to 4000rpm. I shut the AC off and stepped into her WOT to see if maybe it was just something with the AC. It ran WOT a little better but still definitely a problem here.

Here's the problem in sequence (and it wasn't doing this before I put it in the shop to have the AC worked on).

Boost dumping.

I'm dumping boost.

Go to WOT in first gear.

Boost builds normally (I'm thinking there's a delay, it feels different than before ...).

Car accelerates seemingly normally (maybe a little slower than it did before, like it's struggling a little).

Boost gauge climbs and spikes to the far right of the gauge.

Car pulls strong to 4500 to 4800 rpm.

Power builds to 4500 to 4800 rpm and then rapidly falls off like it hit a dead spot.

Boost falls from 15psi (stock gauge) to 10 psi to 5 psi rapidly and needle just bounces on 5psi spastically.

15 psi?

It shouldn't be going into overboost like that.

Engine physically feels like it falls flat on its face and stumbles.

Car doesn't like to pull much past 5psi after that or pull towards redline.

If you do a power run (WOT, all gears) then the car's performance starts to suffer towards the top of second gear and by third gear you're having real stamina problems with boost.

Driving the car like a grandmaw and it's fine. No shuddering, no hesitation. Try to drive it fast and it starts to stumble and have problems. I'm thinking something got left unhooked ... a vacuum line maybe. Wastegate?

So, am I dumping boost or building too much boost and with no way to get rid of it the computer is retarding everything to keep me from launching the head through the hood and into low earth orbit? I'm not sure ...

A few hours pass and ... problem fixed.

It was my fault.

I think.

I think I out-thought myself.

There's a pair of vacuum nipples on the passenger side fender well. When I got the Daytona I noticed these were uncapped, at first I thought maybe a vacuum line was missing and I put it on my To-Do list counting it off to "deferred maintenance" and "25 years worth of catch-up".

After that, the Daytona went into the shop for the next six weeks so I was without the car for nearly a month and a half. When I finally got the Daytona back late last Friday night all I did was drive it home, put it in the garage, popped the hood, put a trickle charger on the battery and saw those uncapped vacuum nipples. Remembering that they were on my To-Do list I reached over to my tool chest, grabbed two vacuum caps and stuck them on.

Problem solved, I thought and mentally marked it off of my To-Do list.

I never thought capping those two lines would vastly affect or degrade the performance of my T-II. I kept the Daytona over the weekend but the AC quit working and the oil was still leaking so I didn't drive her very much and I put her in the shop late Monday (again). Almost all of the week went by I didn't get her back until Thursday late at night. Friday she ran fine (I never got into her, no real need to with the daily commute) and I was more concerned with the AC than any performance issues but I did notice that she was starting to show drivability / performance problems at anything other than grandmaw type driving. Today, finally having some time at last to really spend with the Daytona I took the Daytona out and played with her ... and she started having problems, real problems when I stepped into her. I took her home, lurked, studied, went from computer to garage to computer to garage, lurked and studied and ... I couldn't find any obvious problem. Frustrated, maybe a bit desperated, I got on here and posted a thread.

In following the advice in this thread I traced the vacuum lines from the boost control hardware back to ... the block I had capped off a week ago. No way. That couldn't be the problem ... could it?

Could I be that lucky?

I reached down, took off the two vacuum caps, hopped in and took her for a test drive. A hard test drive. Once she warmed up to normal op temp I stepped into her and started rowing gears ... everything was back to normal. In and out of boost, each gear, just like factory stock. She boosted to normal levels, the wastegate worked, everything sounded normal, acceleration was back to spirited and she took me to 100 plus on a long barren straight away with no trouble at all. Boost held at below 15 psi according to the dash gauge and everything seemed just like it was before. All in all, she ran like she was supposed to so ...

Homer Doh!