okay - car has been running great since the cam install months ago- but starting last week car has been running a little rough-

after the cam and valvetrain install , when i would start the car i would have to give it a good rev and the idle would come down and sit perfectly at 1000 (madz tune to 850... figure its just the tach being off) . if i didnt give it a quick rev the idle would stay to low and car would nearly stall braking or when turning sharply. so i got in habit of just giving it the rev.

This week though car started surging a bit more than usual under 2k - but once i would give her gas the idle would smooth right out and the surging would stop. Now its getting harder and harder to get a consistant idle out of car, and tonight she would idle at 5-600 ... car would bring rev to 1000... then it would drop back.. rev up..drop back. it would do this with car just sitting out of gear idling. Then my low coolant light cam on so i shut her down.

Scanned the car and shes throwing no codes. Once the idle gets correct she runs very strong and gives me no troubles. - Oil pressure sits constant at about 55 , and theres no noises coming from the engine other than the rockers.

So what should i be looking for? Prob check fuel pressure, antifreeze, then test my IAC and TPS sensor. im changing out my plugs and wires this week anyway...

was planning on installing my nitrous this weekend so i gotta figure out this problem first and make sure it isnt something bigger. Any ideas?

 

okay - further reading and thinking it may be vacum.

i lost the hose from my TB to passenger valve cover and right now have one rigged up with a ziptie till i can find the old one in my apartment. so it probably has just worked loose. ill check in the morning

so if theres a very small vacum leak out of here, would this explain my need to rev car to get a good idle at start?

thnx

 

That's probably it. More possibilities are: a dying battery due to the cold weather; fouled spark plug and/or plug wire arcing; opti; fuel pump.

Good luck.

 

well - figured it out- random as it is - the coolant overflow tank which is also the battery tray- seperated from the tray.. this left the top of the coolant tank with a huge hole in it-

must have splashed the opti cause and explains why i got a low coolant light as the thing is empty right now. engine must have warmed up and t-stat opened but there was no more antifreeze.

so... she runs fine now - just need to find a new overflow tank...

 

It makes sense. When the engine gets hot, the coolant expands, and in your case most likely flowed out of that hole.

If you have some money, I would recommend to not even bother with your opti, but get a nice DIS system like the Delteq coil system. It's waterproof and so much better than the opticrap. Just my $0.02

 

lol no way getting another opti - ive installed 3 on the car in the last 3 months while building the engine- keep blowing them...this new one i had it disasembled and everything locktited for a bit more insurance

as for the collant resevoir - it didnt spray out of the top, where it mounts to the battery tray it seperated, and it isnt solid under the tray, so now theres about a 4" hole there..ohh well- just ordered a new one for 20$ -

thnx for the advice though. and def would go with the delteq if i had the money, and time to do it