Richie-Van-GTi 71 2 Cars Posted May 15, 2006 I put a power boost valve in my 1.9 as on the rollers it was running lean at top end with a bit of a misfire. Anyway I found the car to run like a dog with the boost valve, even after coutless tinkers and setting up with a CO reader, also it misfired a bit so I took the boost valve off and replaced it with another fuel regulator which came off my other engine that runs fantastic. However I set it up again and the car idles spot on and it drives nice and quick again but I get a lot of misfiring between 2 and 4k RPM. If I floor it she pulls nice and hard right to the limiter but at lower revs just around town etc she misses all the time. When I took the plugs outto check they were a little sooty from the boost valve but it all brushed off and they looked new again, the plugs themselves have done less than 200 miles as they were put in with the boost valve. Could it be the plugs that are junk? They are the correct NGK plugs for the gti, single spark type. Or could it be something else like leads / dizzy etc. Ive tried the full dizzy and leads etc on other engine and its fine with that no misfires etc but it does have different plugs. Share this post Link to post Share on other sites
pug309twin40s 1 Posted May 15, 2006 check ignition amp or ignition coil. Share this post Link to post Share on other sites
jackherer 543 Posted May 15, 2006 if its running lean there is a reason for that and a boost valve will just mask that rather than cure it. could try a new fuel filter if its not been changed for a while, also worth getting the injectors reconned and tested. Share this post Link to post Share on other sites
Richie-Van-GTi 71 2 Cars Posted May 15, 2006 its had a full service and tried different known good injectors. I think the old regulator got a bit weak hence the lean top end. Could it be TPS causing the issue as it runs fine top end and idles fine, its just inbetween thats the problem. Share this post Link to post Share on other sites
Rob_the_Sparky 9 Posted May 15, 2006 Sounds similar symptoms to my 309, it eventually blew its ignition amp after I fitted a different FPR, rebuilt injectors, new plugs and leads, better dizzy cap and arm in an attempt to solve the problem. If you have an ignition amp in stock I'd try it. Rob Share this post Link to post Share on other sites
Richie-Van-GTi 71 2 Cars Posted May 15, 2006 problem solved and another created, found th spark plug on pot 2 to be cracked. Anyway sorted the misfire and had her pulling like a train to the redline without any flat spots or misses. But then I developed an oil leak, then it dropped to 3 pots and after nursing her home found compression to be down on pots 1 and 2. Looks like HG time, not good this close to FCS. Share this post Link to post Share on other sites
