My First DSM, no bottom end power...

[rlester]

Hi All,

I bought a 91 Eagle Talon AWD Turbo with an automatic. It had a burnt valve, and I pulled the head myself and replaced that valve, and had the rest of them reground, installed new stem seals, basically its a new head. Also installed a new timing belt.

Car is running great, even better since I used injector cleaner and now it starts perfectly and idles smoother. It has plenty of power (over 30km/h) but its a dead dog off the line until the turbo spools up around 30. My timing is set to 7 degrees, the timing belt marks are set correctly, but I wonder if shaving the head 20 thou retarded the cam timing enough to cause this lack of low end? (engine was overheated, it warped the head).

I almost consider this unsafe as I wouldn't want to have to gun it to get out of an intersection to aviod an accident. Not that it will happen, but I'm not used to such a weak bottom end.

Should I advance the timing more? How far can I go? 10 to 15? Also, the fuel economy isn't that great, 25mpg with 60% of that being highway. I blocked off my EGR as I was having idle problems before, but now I'm thinking it was the injectors so I will be putting the proper gasket back on and see if maybe that is part of the mileage issue.

I like this car, its a good performer, but I really wish it was a 5 speed right now.

Another question, is this a TSi model? It was repainted at one time, and I dont see the stickers on the back that say what the model is. Does the TSi get the 185hp engine or the 195?

Thanks.

Ryan.

 

[ddavisaf]

First order of business is preforming a Boost Leak Test.
Running a Compression Test wouldn't be a bad idea also.
Any AWD model is a TSI. Any turbo model is a TSI in fact.
Concerning the Boost Leak Test, you want to hold 20 psi in the intake system for no less than 30 seconds. If it drains down at all you've got a leak. Use soapy water or injector cleaner to try and pin point the leaks. Common places for leaks are injector seals, intake manifold gasket, and the flex portion of the intercooler plumbing.

 

[95blackGsTurbo]

1g DSM's (90-94) had low compression 195hp motor's if you had a manual. You have an auto so you have a 13g turbo instead of a 14b and only make 185hp. Also you only have 2.0L. There isn't that much of a bottom end to start with. If you are turbo FWD you have a TSi. Turbo AWD is the TSi AWD. Also base timing should be at 5 degree's and shaving the head won't effect timing.

 

[rlester]

Shaving the head absolutely changes the cam timing. I did a google and found this quote:

Another sealing requirement for today’s overhead cam engines is maintaining the installed height of the cylinder head. The amount of metal removed when the head is resurfaced can change the installed height and retard cam timing, reduce the volume of the combustion chambers, and consequently increase compression. Too much compression can cause detonation problems, which in turn can lead to premature head gasket failure and overheating.

Here is the link where this is found:

http://www.aa1car.com/library/ar396.htm

I've had this problem on other cars where the head was shaved multiple times, and at that point the car had very little power "out of the hole" so to speak. Had to set the cam one tooth advanced to get it back to where it was. I suspect on the DSM I would have to get adjustable cam sprockets.

I plan on doing a boost test, hopefully I can get it to run better.

 

[95blackGsTurbo]

I meant that shaving it once won't affect anything. I have shaved hundred's of heads. If you have to shave it a second time though you may have bigger problem's than gaining some compression. Since our cars are recommended that you run 91 octane anyways you shouldn't see detonation. Getting adjustable cam gears is just a band-air. You really need to get another head. If you are taking that much off also you won't be able to tension the belt to the proper amount and will cause it to slip easier. Being an interferance motor, shaving to much could cause your valve's to hit your piston's even when in time. Either that or there are companies that make MLS headgasket's a certain amount thicker than normal to compensate. I would not just get a set of adjustable gears though. You have to take A LOT off of a head to get it to change the compression ratio even a half point. I have taken a good chunk off of heads before and changed the compression from 9.0:1-9.2:1. That is a good article don't get me wrong but it deal's mainly with the GM Quad 4 which IMO is the worst motor ever put out by GM. I could start a business just replacing cracked heads and warped heads from those cars. Very poor design on GM's part.

 

[unlmtdndeavor]

i drive a awd and i have to agree with the first gear being pretty weak, but the car does make up well for it in second and third. and your fuel economy is pretty good getting 25mpg. i barely get that when i take a full highway road trip. around town when i do around 40% street and 60% highway i get an average of around 17mpg. you must drive with a real soft foot. so don't worry about your mileage...its great