crcleofdst

this is going to be a long post, so bear with me...

So my car is a 93, touring with 75k, running on the original engine. My mods are a downpipe, and I am venting the bov to atmosphere. I have a boost gauge, and a water temp gauge installed as well. When I purchased the car in may of this year, it was bone stock, and ran perfectly. It idled well, pulled strong, and I had no startup issues. After the installation of my boost gauge, I noticed that on wot, sometimes the boost will spike to 11 or 12, and sort of bounce around. I had done a fair amount of research here, and I decided that a vaccuum hose job was in my future. I went through the motions and removed the uim to reveal the rats nest. I probably should have removed everything, and replaced all of the hoses then, but since the majority of them were still pliable and looked good I only replaced a few. After reassembling everything, and going on a test drive, I realized I had not fixed my problem. I left things alone, and just decided that going wot was a bad idea until I had time to pull everything apart. over the past month or two, I have put less than 200 miles on the car, but it seems to be deteriorating. It started with a drop in vaccuum during idle right after my "hose job". I used to pull between 17 and 18 inHg at idle (about 850-900 rpm), now it idle hunts, and I pull anywhere between 11-16 inHg (at 600-700rpm). I recently found a hose that popped off, and after fixing this, it seems to go between 14 and 16 inHg (still idling at about 700rpm). somewhere around this time I got a cel. it turned out to be a bad Intake air temp sensor which I replaced. I also experienced what I believe to be a flooded engine. I had a hard time starting it one night, and when it finally came to life, there was a shitload of smoke. people here suggested that it came from the excess fuel in the engine. Just to be sure, I did a champagne test and I had no bubbles. the car has not done this since. Some other things that should be noted: I have an exhaust leak right at the downpipe. I also damaged the oxygen sensor during the downpipe install, and I replaced it with the generic $20.00 bosch sensor. I was running very very rich when the intake air sensor went bad, and after replacing it, it still seems a little rich. I have never overheated the engine, and I never went wot without the boost gauge, and havent since I realized I was spiking. I know that my boost problem lies in the vaccuum lines. I think that much is obvious, so Im not really looking for help in that area. I do have some ideas from my research concerning the idle, but Id like to get some opinions here as to where to start. I plan on checking the tps, and I know I need to fix my exhaust leak. I also thought I might have a problem with the injectors, but I might be way off base. any other suggestions of where to look, or what to search for in this forum would be really helpful.

Im also trying to understand vaccuum and how it relates to the engines health. for example: My vaccuum seems low compared to a healthy engine, but I also have idle problems. even when I raise the engine speed, it still seems to be a little rough. (which usually yeilds about 16inHg) If I understand what ive read correctly, a properly idling rotary engine that pulls less than say 16 inHg of vaccuum, indicates low compression and a worn engine. so I guess my question is can misfiring, running rich, or having some other malfunction reduce the vaccuum?

thanks for any help,
John

DaleClark

iTrader: (55)

Few things here.

First off, it takes very little mod-wise to have boost spikes on the stock ECU. Your vacuum lines were probably OK to begin with - live and learn. With just a downpipe and a cat-back on my car I had spiking at transition. You can drill out the primary turbo's pill to help that out as a cheapie fix.

If you have any air leaks after the throttle body, it will big time affect how the car runs and how much vacuum it pulls. Finding leaks can be a little tricky - it doesn't have to be a vacuum line, any place where air can get sucked in will cause a problem. You can use starting fluid to help find the leak - with the car idling, spray starting fluid in little bursts around the intake manifold When the engine sucks the starting fluid in, the car will rev up a little bit. Some times you can also hear and feel the leaks as well.

Dale

palsor1

iTrader: (2)

John,

1. I would start by fixing the stuff you know is wrong, and then go from there. If you have an exhaust leak, fix that and see what happens.

2. Next, since you were running rich, you may have fouled your spark plugs. Pull one out and see if the tip is coated black. If so, you may need to change your plugs.

3. After that, I would start doing what Dale suggested and look for air leaks anywhere in and around your manifolds and throttle body.

4. After that, it's probably worth it to try and pull the UIM again and do all of your hoses and check all of the solenoids, though that's a pretty big job.

Mostly, don't get exasperated, just try one thing at a time and rule out one problem at a time. Keep notes about what you do so you can go back later and check if you've already tried something and how it turned out.

- Andy

crcleofdst

guys thanks for the responses. I will be checking the plugs today, and I will try to get to that exhaust leak as well. I think I may order new uim and throttle body gaskets just in case. I will post my findings.

John

crcleofdst

ok,

changed out the plugs, and they were definetly fouled. leading werent so bad, but the trailing were very black. I did not fix the exhaust leak, as daylight was fading. I did notice that it is running marginally better. still idles low, and hunts, but not rough anymore. When I turn the ac on, everything smooths out, and it idles solid at 900 rpm. It also pulls a lot better in the low end.